Interior of a building project showing wooden stud walls and floor joists by by Henfaes from Getty Images and Canva

small_Interior of a building project showing wooden stud walls and floor joists by by Henfaes from Getty Images and Canva

thumbnail_Interior of a building project showing wooden stud walls and floor joists by by Henfaes from Getty Images and Canva

Designing a timber floor joist for a residential project in Australia involves following the relevant [Australian standards](https://clearcalcs.com/standards) to ensure the safety and structural integrity of the floor system. 

We will compare the step-by-step process of analyzing timber floor joists using manual hand calculation versus using structural design software like ClearCalcs.

_Jump straight to the contents:_ 
- _[Analysing Timber Floor Joist by Hand Calculation](https://clearcalcs.com/blog/timber-floor-joist-australian-standards-example#head1)_
- _[Timber Floor Joist Design to Australian Standards Using ClearCalcs](https://clearcalcs.com/blog/timber-floor-joist-australian-standards-example#head2)_
- _[Timber Floor Joist Case Studies & Best Practices](https://clearcalcs.com/blog/timber-floor-joist-australian-standards-example#head3)_

In this example, we will design a timber floor joist for a residential room with the following specifications:

- **Room Dimensions**: 5 meters (length) x 4 meters (width).
- **Live Load**: 1.5 kPa (15 kg/m²) <br> This includes the weight of furniture, occupants, etc.  AS1170.1 Chapter 3 Table 3.1 details the imposed actions (live loads) that need to be considered for various building types. A uniformly distributed action of 1.5kPa should be considered for a self-contained dwelling.
- **Dead Load**: 0.5 kPa (5 kg/m²) <br> This includes the weight of the floor finish, building services, subfloor, and other fixed loads.

>_**TIP**: Get a [practical guide on things to consider when designing timber floor joists](https://clearcalcs.com/blog/a-practical-guide-to-timber-floor-joist-design-in-residential-construction) and different types of timber floor joists commonly used in residential construction._

## <a name= "head1"></a> Analysing Timber Floor Joist by Hand Calculation

### Step 1: Select a trial timber species and grade:

If the project is subject to joist size requirements, then it is possible that you would select the size first and determine the species and grade based on that size using the supplementary notes provided in [AS 1684](https://clearcalcs.com/standards/SA/AS-1684-2-2010-0), and from there, we can find the suitable timber species, grade, and span based on the size of the floor joist.

However, most projects have flexibility with joist sizes, and builders typically are only able to procure certain timber types due to location or price. 

It is good practice for [engineers](https://clearcalcs.com/persona/structural-engineer) to ask the builder what their timber preferences are in terms of supplier, species, and grade to ensure that the design provided is procurable and buildable. 

So, for this example, we will assume the builder has a preference to use "Hardwood – F8" as the timber species and grade, which is a common type in the "Structural Grade" timber from the [Australian Standard AS 1720.1-2010 - Timber Structures](https://clearcalcs.com/standards/SA/AS-1720-1-2010-0), which provides guidance on timber selection based on the intended use and loading conditions.

### Step 2: Determine a trial joist spacing:

Table 5.3 from [AS 1684.2-2010 - Residential Timber-Framed Construction](https://clearcalcs.com/standards/SA/AS-1684-2-2010-0) specifies the maximum allowed joist spacing based on the floor loading, span, and timber grade, as shown below. 

![[BLOG] floor-joist-example-1.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_1_631c8769bb.png)
_Figure 1: Guidance on maximum allowed joist spacing based on the floor loading, span, and timber grade in AS 1684.2-2010. ([Reference](https://clearcalcs.com/standards/SA/AS-1684-2-2010-0))_

Joists spaced more closely together provide a floor with a greater strength capacity but often can clash with building services, and more joists cost more money. 

For our example, let's assume the builder has requested a joist spacing of 450 mm (0.45 meters), a common spacing in the industry. 

Given the room length of 5 metres, we would have 12 joists.

$5000mm/450mm = 11.1$ 

This can be adjusted later if we cannot determine a suitable section size for our joists.

### Step 3: Calculate the tributary area for each joist:

The tributary area is the portion of the floor that each joist supports. It is generally half of the spacing in each direction for uniform loads.

[To calculate the tributary area](https://clearcalcs.com/blog/what-is-load-and-tributary-width-in-structural-design-an-overview), consider the following.

Tributary Width (TW) = Spacing = $0.45$

Tributary Area (TA) = Tributary Width (TW) x Joist Length (found from the room dimensions) = 
$0.45m x 4 m = 0.405 m²$

### Step 4: Calculate the design moment action for each joist:

For simply supported timber members, moment will always be critical to the design (rather than shear).

[AS 1170.0 Chapter 4](https://clearcalcs.com/standards/SA/AS-NZS-1170-0-2002-0) (excerpt shown below) provides guidance on the load factors and combinations that should be considered for the design load. 

![[BLOG] floor-joist-example-2.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_2_849c1b13f8.png)
_Figure 2: Load factors and combination to be considered for the design load in AS 1170.0 ([Reference](https://clearcalcs.com/standards/SA/AS-NZS-1170-0-2002-0))_

We always take the most significant load combination factors and design timber floor joists (and all structures) in accordance with the worst-case scenario. 

For a floor joist, we will consider the permanent and imposed action loading combination (as wind and earthquake are not relevant) and assign a load factor of 1.2 to the dead load and 1.5 to the live load.

Uniformly Distributed Design Load, $UDL_{joist}$ = 
$$(1.2 x Dead Load (DL_{dead}) + 1.5 x Live Load (DL_{live})) * Tributary Width (TW)$$

Design Load, $UDL_{joist}$ = 
$$(1.2 x 0.5 kPa + 1.5 x 1.5 kPa) * 0.45 m = 1.2825 kN/m$$

Moment Action ($M^{*}$) = 

$$wL^2/8 = 1.2825 N/mm * 4000^2 / 8 = 2,565,000 Nmm$$

### Step 5: Calculate the minimum section modulus for each joist:

As per Section 3.2 of [AS 1720.1 Timber Beam Design](https://clearcalcs.com/standards/SA/AS-1720-1-2010-0), we can solve for the minimum section modulus to achieve limit state design. 

$$M_d = φ*k_1*k_4*k_6*k_9*k_{12}*f_b^{'}*Z$$

Using Limit State Design: 
$M_d$ = design capacity in bending≥ $M^*$v ≥ 2,565,000 Nmm
$φ$ = capacity reduction factor (Clause 2.3 AS 1720.1) = 0.9 (refer table)
$k_1$ = duration of load modification factor (Table 2.3 AS 1720.1) = 0.57 (50+years)
$k_4$ = partial seasoning factor (Table 2.5 AS 1720.1) = 0.7 (seasoned timber)
$k_6$ = temperature modification factor (Clause 2.4.3 AS 1720.1) = 1.0 (ambient conditions)
$k_9$ = modification factor for strength sharing (Clause 2.4.5.3 AS 1720.1) = 
$$g_31+(g_32-g_31 )*(1-2s/L)=1+(1.33-1)*(1-(2*0.45)/4)=1.25575$$
$k_12$ = stability factor (Clause 3.2.4 AS 1720.1) = 1.0 (most conservative value)
$f_b^{'}$ = characteristic value in bending = 8 MPa (stress grade F8)
$Z$ = section modulus of beam about the axis of bending

We can solve for the minimum section modulus to achieve limit state design.

$$Z≥M_d/(φ*k_1*k_4*k_6*k_9*k_12*f_b^{'} )≥(2,565,000 )/(0.9*0.57*0.7*1.0*1.25575*1.0*8)≥711,000mm^3$$

### Step 6: Trial Section Sizes:

By trialing different section sizes, we can find a suitable section that has a section modulus greater than the required above. 

Let’s try a 240 x 45 section.

$$Z=(b*d^2)/6=(45*240^2)/6=432,000mm^3$$

The minimum section modulus needs to be 711,000 cubic millimeters, so we will need to increase the grade of the timber. 

Let’s try a grade of F27.

$$Z≥M_d/(φ*k_1*k_4*k_6*k_9*k_12*f_b^{'} )≥(2,565,000 )/(0.9*0.57*0.7*1.0*1.25575*1.0*27)≥210,671mm^3$$

Using F27 grade timber, we find the 240 x 45 section size suitable.

The spacing of the joists can also be adjusted by making them closer together to achieve smaller minimum section modulus requirements. To adjust the joist size, return to Step 3 and complete the process again. 

### Step 7: Check deflection:

To ensure the serviceability of the floor, we must check deflection as per [AS 1170.1-2002 - Structural Design Actions Part 1: Permanent, Imposed, and Other Actions](https://clearcalcs.com/standards/SA/AS-NZS-1170-1-2002-0). This standard specifies limits on deflection for different floor spans based on floor use.

In our example, the floor span is 5 meters, and we take a maximum allowable deflection of $L/250$ (where L is the span length).

Maximum Allowable Deflection $$ = 5000mm/250 = 20mm$$

Second Moment of Area 

$$ I_x=(bd^3)/12=(45*240^3)/12=51,840,000mm^3$$

$$δ=((5wL^4))/((384EI))=((5*1.2825*5000^4))/((384*18500*51,840,000))=11mm $$

The deflection is within the limits. The selected joist size is suitable for the [residential project](https://clearcalcs.com/use-case/residential-design) as per [Australian standards](https://clearcalcs.com/standards).

Please note that this example provides a simplified outline of the design process, and in a real-world scenario, a qualified [structural engineer](https://clearcalcs.com/persona/structural-engineer) should perform a comprehensive analysis considering all applicable factors and standards for accurate and safe design. 

Always consult the relevant Australian standards and seek professional advice when designing structural elements for a project.

## <a name= "head2"></a>  Timber Floor Joist Design to Australian Standards Using ClearCalcs

The [Timber Beam Calculator to AS 1720.1:2010](https://clearcalcs.com/calculations/timberComplexBeam) enables you to do quick and powerful design and analysis for simple and continuous timber beams, with unlimited supports and loads. 

The member selector tool, which has a library of thousands of common timber sections, allows you to get instant results for moment, deflection, and shear, which means that engineers don’t have to iteratively perform calculations as with the worked example by hand above which saves heaps of time!

### Step 1: Enter the Key Properties

From our example above, we have a joist length of 4000mm that is simply supported. So we'll just need to enter the total beam length and the support positions into the support table.

![[BLOG] floor-joist-example-3.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_3_b8b29020d0.png)

### Step 2: Enter the Loads

Live load: 1.5 kPa (15 kg/m²)

This includes the weight of furniture, occupants, etc. AS1170.1 Chapter 3 Table 3.1 details the imposed actions (live loads) that need to be considered for various building types. For a self-contained dwelling, a uniformly distributed action of 1.5kPa should be considered.

Dead load: 0.5 kPa (5 kg/m²)

This includes the weight of the floor finish, building services, subfloor, and other fixed loads.

Floor joists only bend about the major axis.

![[BLOG] floor-joist-example-4.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_4_1ac363a5e1.png)

### Step 3: Check the Design Criteria, Member Properties and Modifications Factors

By default, the ClearCalcs Timber Calculator already has the Design Criteria, Member Properties, and Modifications Factors prefilled based on the inputs provided in the Key Properties and Loads.  

![[BLOG] floor-joist-example-5.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_5_1d06266028.png)

Some of these can be manually changed, and clicking on each input will provide a description of the parameter as well as the relevant Australian Standard to refer to for further information. 

For example, if you would like to know more about the Equilibrium Moisture Content (EMC) value used in the calculation, the calculator shows that it is based on Clause 2.4.2.3 of the AS 1720.1:2010.

![[BLOG] floor-joist-example-6.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_6_b10e0a083f.png)

### Step 4: Assess Summary Outputs

The summary outputs provide immediate feedback for the design and detail the utilization of the moment, shear, bearing, and deflection capacity.

![[BLOG] floor-joist-example-7.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_7_8799975ddd.png)

### Step 5: Optimise the Design

The member selector tool has thousands of standard grades and sizes of timber and provides immediate feedback on the utilization of their moment, shear, bearing, and deflection capacity. 

Users can use this tool to provide the most efficient design possible, ensuring that members aren’t unnecessarily oversized (utilization <50%) or undersized (utilization>100%). 

![[BLOG] floor-joist-example-8.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_example_8_7eb50749e3.png)

This can help reduce material costs for the builder and is also environmentally efficient.

## <a name="head3"></a> Timber Floor Joist Case Studies & Best Practices

### Case Study 1: Open-Concept Multi-Level Living Space

#### Description 

In this residential project, the design called for an open-concept living space with multiple levels and a seamless connection between different areas. Timber floor joists were creatively used to achieve a visually appealing and functional interior.

![[BLOG] floor-joist-case-study-1.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_case_study_1_a6a35ad861.png)
_Figure 3: An example of open-concept living space_

#### Innovative Use

Cantilevered Timber Floor Joists

#### Best Practices
- **Structural Analysis**: Before implementing cantilevered timber floor joists, a thorough structural analysis was conducted to ensure that the selected timber species and grade could support the intended loads without compromising safety and stability. Shear and deflection become critical for cantilevered members.
- **Expert Engineering**: A qualified structural engineer worked closely with the [architect](https://clearcalcs.com/persona/architect) and construction team to design the cantilevered floor system. The engineer accounted for factors like deflection, vibration, and load distribution to ensure the best possible performance.
- **Timber Selection**: High-quality, durable timber with the appropriate strength and structural properties was chosen. The timber species and grade were carefully selected to meet the design requirements and comply with relevant Australian standards. 

### Case Study 2: Sustainable Commercial Building

#### Description

A commercial office building aimed to be environmentally friendly and promote sustainability throughout its design. Timber floor joists played a crucial role in achieving this objective.

![[BLOG] floor-joist-case-study-2.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_case_study_2_702e8aa104.png)
_Figure 4: An example of a commercial space with timber floor joists_

#### Innovative Use

Glue-Laminated Timber (Glulam) Floor Joists

#### Best Practices
- **Sustainable Material**: Glulam, made from laminated layers of sustainably sourced timber, was used as an eco-friendly alternative to traditional solid timber or steel. The building's sustainability goals were met by reducing the carbon footprint associated with construction materials.
- **Fire Resistance**: The glulam timber used in the floor joists was treated with fire-retardant coatings to enhance fire resistance, making it compliant with relevant fire safety regulations.
- **Quality Control**: Quality control measures were implemented throughout the manufacturing process of glulam timber to ensure uniformity and structural integrity. Adherence to Australian standards for glulam production was paramount.

### Case Study 3: Adaptive Reuse of Industrial Space

#### Description

An old industrial building was repurposed into a modern co-working space that preserved its industrial charm. Timber floor joists were an essential component in the adaptive reuse of the space.

![[BLOG] floor-joist-case-study-3.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_case_study_3_d760e3beb2.png)
_Figure 5: An example of converted building with exposed timber floor joists_

#### Innovative Use

Exposed Timber Floor Joists

#### Best Practices
- **Structural Evaluation**: The existing timber floor joists were thoroughly inspected by structural engineers to assess their condition and capacity. Any damaged or weak joists were repaired or replaced, ensuring safety and stability.
- **Architectural Aesthetics**: The original timber floor joists were left exposed, adding character and a rustic ambiance to the co-working space. Careful consideration was given to their arrangement to create visually appealing patterns.
- **Acoustic Treatment**: To control noise transmission between different areas of the co-working space, acoustic treatments were incorporated into the design. Sound-absorbing materials were strategically placed to minimize noise disruptions.

## Overall Best Practices for Timber Floor Joists:
- **Compliance with Standards**: All designs and installations should comply with relevant Australian standards for timber structures, ensuring safety and meeting legal requirements.
- **Professional Expertise**: Qualified structural engineers and architects should be involved in the design process to ensure proper analysis, selection of suitable timber, and adherence to best practices.
- **Regular Maintenance**: Timber floor joists should undergo regular inspections and maintenance to identify any issues and prolong their service life.
- **Sustainable Sourcing**: Use sustainably sourced timber or timber alternatives to promote environmental consciousness in construction projects whenever possible.
- **Fire Safety**: Implement appropriate fire-retardant treatments and measures as building codes and regulations require.

By applying these best practices and embracing innovative uses, timber floor joists can be utilized effectively and safely to create unique and sustainable spaces in various construction projects.

Explore the benefits and drawbacks of analyzing timber floor joist design through manual calculation versus ClearCalcs structural design software. Determine the most accurate, efficient, and cost-effective approach for informed decision-making on your construction projects.

Analysis and Design of Timber Floor Joists to Australian Standards

A pattern of wood floor joist in new construction by valentynsemenov from Canva

small_[BLOG] floor-joist-overview-0.png

thumbnail_[BLOG] floor-joist-overview-0.png

[BLOG] floor-joist-overview-0.png

## Introduction

Timber floor joists are essential structural elements in [residential construction](https://clearcalcs.com/use-case/residential-design), providing support and stability to the flooring system. 

This article aims to provide [structural engineers](https://clearcalcs.com/persona/structural-engineer), [building designers](https://clearcalcs.com/persona/building-designer), and [architects](https://clearcalcs.com/persona/architect) with a comprehensive understanding of timber floor joist design, specifically focusing on [Australian standards and building codes](https://clearcalcs.com/standards). 

_Jump to Contents_
- _[Timber Floor Joists Design Considerations](https://clearcalcs.com/blog/a-practical-guide-to-timber-floor-joist-design-in-residential-construction#head1)_
- _[Relevant Building Codes and Industry Standards in Australia](https://clearcalcs.com/blog/a-practical-guide-to-timber-floor-joist-design-in-residential-construction#head2)_
- _[Design Process of a Residential Floor Joist to Australian Standards](https://clearcalcs.com/blog/a-practical-guide-to-timber-floor-joist-design-in-residential-construction#head3)_
- _[Exploring Different Types of Timber Floor Joists](https://clearcalcs.com/blog/a-practical-guide-to-timber-floor-joist-design-in-residential-construction#head4)_

We will explore design considerations such as load-bearing capacity, span length, deflection, and vibration. Additionally, we will delve into different types of timber floor joists commonly used in residential construction, including traditional solid timber joists and engineered timber I-beam joists, as well as briefly discuss alternative engineered floor joist systems.

![A pattern of wood floor joist in new construction by valentynsemenov from Canva](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_floor_joist_overview_0_00d6abfa97.png)
_Figure 1: An example of timber floor joist in a new house construction_

## <a name="head1"></a> Timber Floor Joists Design Considerations

Designing timber floor joists requires careful consideration of various factors to ensure structural integrity and safety. The following key considerations must be addressed:

### Load-bearing capacity

Determining the maximum loads the floor joists will bear is crucial. This includes both dead loads (weight of the structure itself and permanent fixtures) and live loads (occupant loads and furniture).

### Span length

The span length refers to the distance between supports and affects the joists' dimensions and spacing. Longer spans require larger and stronger joists.

### Deflection

Excessive deflection can lead to an uncomfortable or unstable floor. Australian standards specify maximum allowable deflection limits based on the floor's intended use and occupant expectations.

### Vibration

Proper floor joist design should consider mitigating vibrations caused by occupant movement or equipment. This is particularly important for floors with sensitive equipment or activities.

## <a name="head2"></a> Relevant Building Codes and Industry Standards in Australia

Compliance with building codes and industry standards is essential in timber floor joist design. In Australia, the following codes and standards are applicable:
- **[The National Construction Code (NCC)](https://ncc.abcb.gov.au/)**: Part 3.1.2 and Part 3.5 of the NCC provide requirements for structural design, including floor joists, in residential buildings.
- **[Australian Standard AS 1684](https://clearcalcs.com/standards/SA/AS-1684-2-2021-0)**: Residential Timber Framed Construction: This standard provides detailed guidelines for timber framing, including design procedures, materials, and connections.
- **[AS 1720.1](https://clearcalcs.com/standards/SA/AS-1720-1-2010-0)**: Timber Structures: Design Methods: This standard offers comprehensive guidance on the design of timber structures, including floor joists, with specific provisions for different load types and environmental conditions

## <a name="head3"></a> Design Process of a Residential Floor Joist to Australian Standards

### 1. Load Calculation

To calculate the total design load on the floor joist, we need to consider both the live load and the dead load and the critical load combination. 

For determining the critical load combinations and structural design actions for a timber floor joist in Australia, you should refer to the [Australian Standard AS/NZS 1170:2002 - Structural Design Actions](https://clearcalcs.com/standards/SA/AS-NZS-1170-0-2002-0). 

This standard provides general principles and requirements for determining loads and actions that need to be considered in the design of structures, including timber floor joists. 

[AS1170.1 Chapter 3](https://clearcalcs.com/standards/SA/AS-NZS-1170-1-2002-0) details the dead loads and live loads that need to be considered, [AS 1170.2](https://clearcalcs.com/standards/SA/AS-NZS-1170-2-2021-0) details wind loads, [AS 1170.3](https://clearcalcs.com/standards/SA/AS-NZS-1170-3-2003-0) considers snow loading and [AS 1170.4](https://clearcalcs.com/standards/SA/AS-1170-4-2007-0) considers earthquake loading (snow and earthquake are typically not applicable to floor joists). 

[AS 1170.0 Chapter 4](https://clearcalcs.com/standards/SA/AS-NZS-1170-0-2002-0) (shown below) provides guidance on the load factors and combinations that should be considered for design. Generally, in timber design, we always take the most significant load combination factors and design timber floor joists (and all structures) in accordance with the worst-case scenario.

![Section 4.2.2 in AS/NZS 1170.0:2002 - Structural design actions, Part 0: General principles](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_overview_1_51ee613c82.png)
_Figure 2: Section 4.2.2 of AS/NZS 1170.0:2002 outlining the load factors and combinations for structural design. ([Reference](https://clearcalcs.com/standards/SA/AS-NZS-1170-0-2002-0))_

Additionally, you should also refer to the specific requirements and guidelines for timber structures as outlined in [AS 1720.1:2010 - Timber Structures, Part 1: Design Methods](https://clearcalcs.com/standards/SA/AS-1720-1-2010-0). This standard deals specifically with design methods for timber structures, including floor joists, and provides detailed information on material properties, member design, load combinations, and more.

### 2. Joist Size Determination

To determine the required size of the floor joist, we need to consider the span length, load, and the appropriate design criteria specified in AS 1684 and AS 1720.1. AS 1720 can be used to design timber members from first principles and a detailed example of this will be provided in a subsequent blog post.

To speed up the design process, the supplementary notes provided in AS 1684 provide span tables, and from these we can find the suitable timber species, grade, and size of the floor joist. Take a look at the example below for grade F27 seasoned hardwood with a floor load width of 3600mm.

![[BLOG] floor-joist-overview-5.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_overview_5_73c80546a0.png)
_Figure 3: An example of span table for floor joist provided in AS 1684 supplementary notes._

### 3. Connection Details

There are several types of connections used for timber floor joists, each serving different purposes and providing varying levels of strength and stability. The choice of connection depends on the specific structural requirements, loads, and other factors of the construction project. Here are some common types of connections for timber floor joists:

1. **Nailing**: Nailing is one of the simplest and most common methods of connecting timber floor joists. Joists are typically nailed to beams or other supporting elements using [nails](https://clearcalcs.com/calculations/timberNail) or [screws](https://clearcalcs.com/calculations/timberScrew). Toe-nailing and face-nailing are two common nailing techniques used for securing joists to beams or headers.
2. **Joist Hangers**: Joist hangers are metal brackets designed to hold the ends of the floor joists and attach them to beams or headers. They provide strong and reliable connections while allowing the joists to be flush with the supporting member.
3. **Ledger Strips**: Ledger strips are horizontal wooden members attached to the side of a beam or wall. The ends of the floor joists can be secured to these ledger strips using nails or screws.
4. **Timber Connectors**: Timber connectors are metal brackets and hardware specifically designed for connecting timber members. They offer enhanced strength and stability compared to standard nailing or screwing.
5. **Through-Bolts**: Through-bolts are long bolts that pass through the entire depth of the joist and connect it to the supporting element. They provide a very strong connection but may require pre-drilling holes in the timber to avoid splitting.
6. **Notched Connection**: In this method, a notch or groove is cut into the supporting beam or header, and the end of the joist fits into the notch. This type of connection creates a flush surface and enhances stability.
7. **Bridging or Blocking**: Bridging or blocking involves adding small timber pieces between adjacent joists to provide lateral support and prevent twisting or buckling of the joists.
8. **Metal Plates or Gussets**: Metal plates or gussets can be used to reinforce connections between timber members. They are typically secured with nails or screws and provide added strength and durability.
9. **Adhesive Bonding**: In some cases, structural adhesive can be used along with mechanical fasteners to enhance the connection between timber members.

The connection details between the floor joists and supporting members, such as bearers or walls, are crucial for structural integrity. AS 1684 provides guidelines for the appropriate connection methods and fastener sizes.

For example, the connection between the joist and the bearer could involve using a specific size and type of nails or screws at designated spacing.

It is important to consult AS 1684 for the specific connection requirements based on the selected timber species, grade, and size of the floor joist.

### 4. Calculation Verification

Engineers should always verify their design to ensure accuracy. Structural design and analysis software like [timber beam calculator](https://clearcalcs.com/calculations/timberComplexBeam) with built-in presets for common timber structures like floor joists, floor bearers, and floor lintels can speed up the calculation and verification process.

For example, [structural engineer Matt Ward uses common presets like deck joists and deck beams for his residential design](https://clearcalcs.com/customers/ward-engineering) to make his workflow more efficient, saving valuable time. 

Additionally, users can input their loading conditions and assess the adequacy of a range of joists from known Australian manufacturers using the member selector tool instantaneously. 

This can ensure the selected timber joist is the most efficient member and can be procured by the builder.

![[BLOG] floor-joist-overview-2.png](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_floor_joist_overview_2_773c3e7d66.png)
_Figure 4: A database of timber joists from common Australian manufacturers showing how they are automatically checked to asses their loading condition in ClearCalcs floor joist calculator._

## <a name="head4"></a> Exploring Different Types of Timber Floor Joists

### Traditional Solid Timber Joists

Traditional solid timber joists, commonly made from dimensional lumber, have been used for many years in residential construction. 

Key characteristics and applications include:
- Characteristics: Solid timber joists are typically made from softwood species such as pine or spruce. They are available in standard sizes, with rectangular or square cross-sections.
- Applications: Solid timber joists are well-suited for residential floors with shorter spans and lighter loads. They are cost-effective and widely available.
- Benefits and Limitations: Solid timber joists offer simplicity in design and construction. However, they have limitations in longer spans and may be susceptible to warping, twisting, or shrinking over time.
 
### Engineered Timber Joists

Engineered timber I-beam joists have gained popularity in residential construction due to their superior performance and design flexibility. 

They are constructed from various types of engineered timber products, such as laminated veneer lumber (LVL), oriented strand board (OSB), glue-laminated timber (Glulam) or laminated strand lumber (LSL). They are manufactured by arranging layers of lumber pieces with their grain running parallel and then gluing them together under high pressure and heat. 
![Material Properties are Aligned to Achieve Greater Efficiency in Engineered Timber Members](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_overview_3_4eb69b0dd5.jpg)
_Figure 3: Material properties are aligned to achieve greater efficiency in engineered timber members. ([Reference](https://kapstorygroup.com/en/application/performance-and-nominal-sizes))_ 

This process creates a continuous, strong, and stable member that can be custom-shaped to meet various design requirements. 

Key benefits and advantages include:
- Enhanced strength-to-weight ratio: Engineered I-beam joists utilize a combination of timber products, adhesives, and steel fasteners, resulting in high strength and stiffness with reduced weight.
- Consistency and predictability: Engineered joists are manufactured with precise specifications, ensuring consistent performance and eliminating variability often found in solid timber joists.
- Resistance to warping and shrinking: Engineered joists are less prone to warping, twisting, or shrinking compared to solid timber joists, ensuring a more stable and durable floor system.
- Design flexibility: Engineered joists can accommodate larger spaces as the better utilise the material properties of the timber and creative architectural designs due to their longer spans and ability to carry heavier loads.
- Environmental considerations: Engineered timber products often utilize sustainable sourcing practices and contribute to reducing waste in the construction industry.
- Common use cases: Engineered I-beam joists excel in applications that require longer spans, such as open floor plans, vaulted ceilings, and areas where mechanical systems need to pass through the floor.

### Other Types of Engineered Floor Joists

While the focus of this article has been on solid timber and I-beam joists, it's worth mentioning alternative engineered floor joist systems, including trusses and open-web joists. These systems offer unique features, benefits, and specific use cases:

#### Trusses

[Trusses consist of interconnected structural members](https://clearcalcs.com/blog/what-is-truss) and are commonly used for larger spans, such as roof structures. 

Trusses offer clear spans and make installation of plumbing and electrical services easy. The key advantage of trusses is that their members are loaded axially, thus eliminating any shear or bending. In other words, they are either in compression or tension, or have no force at all (zero force members). This makes trusses highly efficient as a structural component and enables them to achieve greater spans than solid timber joists.

![An image illustrating trusses made from timber and steel](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_materials_c7dc83fd07.jpg)
_Figure 4: Example of timber and steel trusses. ([Reference](https://freimans.com/metal-vs-timber-why-its-better-to-use-timber-trusses/))_

_For more resources on truss design, check out these other guides and resources:_
- _[Types of Roof Trusses and Their Applications in Residential Design](https://clearcalcs.com/blog/types-of-roof-trusses)_
- _[What is a Truss and How Do Trusses Work in House Framing Design?](https://clearcalcs.com/blog/what-is-truss)_

#### Open-Web Joists

Open-web joists, also known as metal-web joists, utilize a combination of steel and timber components. They offer design flexibility and ease of installation that allows for efficient routing of mechanical services. They also offer greater spans than solid timber joists.

![An example of open web joists](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_floor_joist_overview_4_1967454221.jpg)
_Figure 5: An example of open-web joists. ([Reference](https://www.donaldsontimberengineering.co.uk/products/joists/open-web-joists/))_

## Conclusion

Timber floor joist design in residential construction requires a thorough understanding of load-bearing capacity, span length, deflection, and vibration considerations. Compliance with relevant building codes and standards, such as the NCC, AS 1684, and AS 1720.1, is crucial. 

Traditional solid timber joists are suitable for shorter spans, while engineered timber I-beam joists provide enhanced strength-to-weight ratio, design flexibility, and improved resistance to warping. 

Alternative engineered floor joist systems like trusses and open-web joists offer additional options for specific applications. 

By considering these factors and employing sound engineering principles, structural engineers can ensure the safe and efficient design of timber floor joists in residential construction projects in Australia.

This article aims to provide structural engineers, builders, and architects with a comprehensive understanding of timber floor joist design, specifically focusing on Australian standards and building codes. 

A Practical Guide to Timber Floor Joist Design in Residential Construction

Strong wind and bad weather symbol by Jozsef Soos from Getty Images via Canva

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## Introduction 

Wind load analysis, which involves the computation of forces exerted by the wind on structures, is a crucial aspect of [structural engineering](https://clearcalcs.com/use-case/structural-design). [Wind can exert significant lateral forces on a structure](https://clearcalcs.com/blog/load-transfer-in-residential-structures-from-roof-to-foundation), which can cause it to sway or even collapse if it is not properly designed to withstand these loads. 

_Table of Contents:_
- _[Key Considerations of Wind Load Analysis](https://clearcalcs.com/blog/wind-load-analysis-to-asce-7-a-guide-for-structural-engineers#head1)_
- _[Wind Load Analysis for MWFRS](https://clearcalcs.com/blog/wind-load-analysis-to-asce-7-a-guide-for-structural-engineers#head2)_
- _[Wind Load Analysis for Components and Cladding](https://clearcalcs.com/blog/wind-load-analysis-to-asce-7-a-guide-for-structural-engineers#head3)_

To ensure the integrity of the structure is maintained, [structural engineers](https://clearcalcs.com/persona/structural-engineer) must take steps to accurately analyze and transfer these lateral loads using various structural elements. By doing so, they can help to ensure that the building remains stable and safe for its occupants, particularly in regions prone to severe weather conditions such as hurricanes or typhoons.

[The American Society of Civil Engineers (ASCE)](https://www.asce.org/) has established a set of standards known as [ASCE 7](https://www.asce.org/publications-and-news/asce-7) to ensure consistency, accuracy, and safety of built structures. 

The guidelines provide a framework for accurate calculations based on geographical location, building characteristics, and wind speeds. 

## <a name ="head1"></a> Key Considerations of Wind Load Analysis 

Overall, wind load analysis begins with determining the risk category of the building ([using Table 1.5-1 of ASCE 7-16](https://ascelibrary.org/doi/book/10.1061/9780784414248)). 

### Wind Speed

The most critical aspect of wind load analysis is obtaining the basic wind speed, $V$, where the building is located. Wind speed is typically sourced from related code-based maps, such as that provided by ASCE 7-16 Figure 26.5-1A to D and Figure 26.5-2A to D (see Figure 1), or local meteorological records. 

![An example of a basic wind speed map as per the ASCE 7-16](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_wind_analysis_asce_7_16_wind_hazard_map_6338c139aa.png)
_Figure 1: Figure 1. An example of a basic wind speed map as per Figure 26.5-1A in ASCE 7-16 ([Reference](https://ascelibrary.org/doi/book/10.1061/9780784414248))_

The process then identifies wind load parameters including wind directionality, exposure category, topography, and ground elevation.

### Wind Directionality Factor

Wind directionality in wind load analysis refers to the consideration of how wind flows around and interacts with a building. It takes into account the shape, size, and height of the structure, as well as its surrounding terrain. 

Wind directionality is crucial in determining the magnitude and distribution of wind loads on a building. For low-rise buildings, such as residential houses or small commercial structures, the simplified method to consider wind directionality is normally used, and the wind directionality factor, $K_d$, can be obtained from [Table 26.6-1 of ASCE 7-16](https://ascelibrary.org/doi/book/10.1061/9780784414248).

### Exposure Category

We can determine the exposure category based on ground surface topography, vegetation, and built structures.

In ASCE 7-16 (section 26.7), the following exposure categories can apply in wind load calculations: 
- **Exposure B** - Urban/wooded areas with many obstructions
- **Exposure C** - Open terrain with scattered obstructions
- **Exposure D** - Flat unobstructed terrain

When it comes to residential design, structural designers tend to take a cautious approach by considering the worst possible scenario when selecting an exposure category. For example, if you are constructing a building at the edge of a new development and one side is exposed to Category B while the other side faces Category C, the general practice is to opt for Category C as the conservative choice.

### Topographic Factors 

When building on hills, ridges, or escarpments as low as 15 feet, wind load calculations must consider the topographic factor, $K_{zt}$, which accounts for increased wind speeds due to local topography. 

$$K_{zt}=(1+K_1 K_2 K_3 )^2$$

Where: 
- $K_{zt}$  = Topographic factor
- $K_1$ = Factor to account for shape of topographic feature and maximum speed-up effect.
- $K_2$ = Factor to account for reduction in speed-up with distance upwind or downwind of crest.
- $K_3$ = Factor to account for reduction in speed-up with height above local terrain.

### Ground Elevation

Areas with higher elevations have lower air density, resulting in reduced wind loads. In wind loads calculation, the ground elevation factor is used to adjust for air density, $K_e$, and can be obtained from Table 26.9-1 in ASCE 7-16.

### Building Enclosures

Another important factor to consider in wind load analysis is the building enclosure. The principle behind this is to consider the difference in pressure between the inside and outside of the building. 

ASCE 7 has classified building enclosures into four categories:
- **Enclosed**: Air generally doesn’t come in. Wind pressure outside.
- **Partially enclosed**: Air flows into the building, but can’t escape.
- **Open**: Air flows into the building, and can escape
- **Partially open**: Air flows through the building

![Illustration of enclosed building and partially enclosed building and the effect wind direction on internal and external pressures. ](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_wind_analysis_wind_pressures_enclosures_c8d2f4b95e.jpg)
_Figure 2: Illustration of enclosed building and partially enclosed building and the effect wind direction on internal and external pressures. ([Reference](https://seblog.strongtie.com/2013/02/open-front-structure-wind-pressure-design/))_

These parameters play a substantial role and can drastically influence the wind pressures experienced by a building and contribute to the subsequent steps of wind load calculations, such as internal pressure coefficient, $GC_{pi}$, external pressure coefficients, and wind pressure, $P$. 

The wind pressures is determined with the following equation: 

$$p= q_h[(GC_{pf}) − (GC_{pi})](lb/ft^2)$$

Where: 
- $q_h$ = velocity pressure evaluated at mean roof height $h$
- $GC_{pf}$  = external pressure coefficients from Fig. 28.3-1 of ASCE 7-16 (see Figure 3)
- $GC_{pi}$ = internal pressure coefficient from Table 26.13-1 of ASCE 7-16

This article primarily focuses on applying [wind load calculations](https://clearcalcs.com/calculations/loadsWindCnCASCE7-16) for two commonly used systems in residential and light commercial projects: the main wind-force resisting system (MWFRS) and the components and cladding systems of structures. 

## <a name="head2"></a>Wind Load Analysis for MWFRS

The **main wind-force resisting system**, or **MWFRS**, is an ensemble of structural elements designed to take on lateral and vertical wind loads, including structural walls, columns, rigid frames, and bracing systems. 

The MWFRS is vital as it forms the backbone of any structure, ensuring overall stability against wind forces by transferring these wind loads. The mechanism involves transmitting wind forces from their point of application, typically the external envelope of the building, through the structural system and ultimately to the ground, thereby ensuring the building remains upright and secure. 

For the MWFRS wind loads calculation, ASCE 7-16 presents two methods: The **Directional Procedure**, which is widely used for all building types, and the **Envelope Procedure**, which specifically applies to low-rise buildings and is the primary focus of this article.

The following table outlines the steps required to determine the MWFRS wind loads using the envelope procedure:
- **Step 1**: Determine the risk category of the building
- **Step 2**: Determine the basic wind speed, $V$
- **Step 3**: Determine wind load parameters: 
    - Wind directionality factor, $K_d$ 
    - Exposure category 
    - Topographic factor, $K_{zt}$ 
    - Ground elevation factor, $K_e$ 
    - Enclosure classification
    - Internal pressure coefficients, $GC_{pi}$
- **Step 4**: Determine velocity exposure coefficient
- **Step 5**: Determine velocity pressure
- **Step 6**: Determine external pressure coefficient, $GC_p$, based on Figure 28.3-1 for flat and gable roofs
- **Step 7**: Calculate wind pressure, $p$

![[BLOG] wind-analysis-mwfrs.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_wind_analysis_mwfrs_1e82f482cc.png)
_Figure 3: An example of how external pressure coefficients are calculated for MWFRS loads with enclosed and partially enclosed buildings with low-rise walls and roofs. ([Reference](https://ascelibrary.org/doi/book/10.1061/9780784414248))_

## <a name="head3"></a>Wind Load Analysis for Components and Cladding

**Components and cladding systems** pertain to the exterior elements of a structure, such as roofs and walls. These elements directly interact with the wind and are subject to different wind pressures. 

While the MWFRS ensures overall structural stability against wind loads, the significance of components and cladding in wind load analysis arises from their crucial role in withstanding localized wind pressures, safeguarding the building's integrity, and protecting its occupants. 

There are distinct differences in the design considerations for the MWFRS and components and cladding systems. While the MWFRS is designed to counter wind loads from any direction, ensuring overall structural stability, the components and cladding system are primarily evaluated for wind loads that are normal or perpendicular to the surface. 

According to the ASCE 7 guidelines, similar to the MWFRS, calculating wind loads for components and cladding systems starts with determining the risk category and basic wind speed. 

However, additional factors come into play in the case of components and cladding systems. The effective wind area, which is the area that the wind load is distributed over, is a key factor in these calculations. 

The external pressure coefficients, $GC_p$, an example given in Figure 4, also come into consideration, determined by the specific component's shape, angle, and location on the building.

![Wind zones for components and cladding system](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_wind_analysis_components_cladding_e92b1d28e8.png)
_Figure 4. An example of the external pressure coefficients for components and cladding system with enclosed or partially enclosed walls and flat, gable, hip, or monoslope roofs. ([Reference](https://clearcalcs.com/calculations/loadsWindCnCASCE7-16))_

Similarly, the pressure coefficient values would differ for windows and doors, which often serve as pressure release points during extreme wind events. Their design must withstand not only the direct wind loads but also the rapid changes in pressure caused by gusty winds or the event of a sudden windstorm.

The following table outlines the steps required to determine the components and cladding wind loads:
- Step 1: Determine the risk category of the building
- Step 2: Determine the basic wind speed, $V$
- Step 3: Determine wind load parameters:
    - Wind directionality factor, $K_d$
    - Exposure category
    - Topographic factor, $K_{zt}$
    - Ground elevation factor, $K_e$
    - Enclosure classification
    - Internal pressure coefficients, $GC_{pi}$
- Step 4: Determine velocity exposure coefficient
- Step 5: Determine velocity pressure
- Step 6: Determine external pressure coefficient, $GC_p$
    - Walls
    - Flat roofs, gable roofs, hip roofs
    - Monoslope roofs
- Step 7: Calculate wind pressure, $p$

## Conclusion

Wind load analysis is an essential aspect of structural engineering that cannot be overlooked if we want to ensure the stability and safety of buildings against wind forces.

In the United States, the ASCE 7 guideline is the go-to resource for wind load calculations. This guideline takes into account several factors, including wind speed, wind directionality factor, exposure category, topographic factors, ground elevation, and building enclosure.

For residential or light commercial projects, wind load analysis is typically used for two systems: the main wind-force resisting system (MWFRS) or components and cladding systems. By conducting a thorough wind load analysis, we can guarantee the safety and durability of buildings in the face of harsh wind conditions.

### Frequently Asked Questions about ASCE 7

#### What is the difference between ASCE 7-16 and ASCE 7-22?

The ASCE frequently revises its guidelines to incorporate recent advancements in research, technology, and industry practices. The update from ASCE 7-16 to ASCE 7-22 reflects these changes.

The International Building Code (IBC) incorporates ASCE 7-16, which was published in 2016, in its latest 2021 edition. 

Looking ahead to the upcoming 2024 edition of the IBC, it is highly likely that it will continue to adopt ASCE 7 as the primary reference for design loads. The IBC typically aligns with the most recent edition of ASCE 7-22 to incorporate the latest advancements and research in structural engineering.

### Ready to start calculating in ClearCalcs?

[You can use the account for 14 days for free](https://clearcalcs.com/signup), with no commitment required. Need ClearCalcs for a one-off project? Subscribe to our month-to-month plan and cancel anytime, no questions asked.

Learn how engineers calculate wind loads for MWFRS and components and cladding system per ASCE 7-16.

Wind Load Analysis to ASCE 7: A Guide for  Structural Engineers

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This month, we are introducing the release of Restrained (Basement) Retaining Wall, an update to the Wood Shear Wall Calculator that includes support for multi-story buildings and more.

Let's dive right into it.

## Retaining Wall

### Restrained (Basement) Retaining Wall now available to IBC 2021, ACI 318-19

Meet our latest calculator: [Restrained Basement Retaining Wall Calculator](https://clearcalcs.com/calculations/retainingWallRestrainedUSA). 

The calculator quickly analyzes and calculates designs for restrained retaining walls, which are typically used as basement walls.

Built to comply with the International Building Code (IBC) 2021, the calculator assumes the absence of shear keys, no inclination of soil behind the structure, and excludes wind or earthquake loads.

With an easy-to-use interface for you to input the retaining wall, soil, and stem wall properties, you will instantly obtain the sliding and lateral forces, moment, and shear capacity of your restrained retaining wall's stem and footing in minutes.

[Watch the calculator in action](https://clearcalcs.wistia.com/medias/vk04a4r3jl).

![calcsUS-basement-retaining-wall-key-dimensions.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/calcs_US_basement_retaining_wall_key_dimensions_b87a90fbf9.png)

The calculator also checks for negative moments in the stem wall, making it really simple to help you select the appropriate reinforcement placement for your basement retaining wall.

![calcsUS-basement-retaining-wall-reinforcement-placement-small.png](https://clearcalcs-prod2-cms.s3.amazonaws.com/calcs_US_basement_retaining_wall_reinforcement_placement_small_6746d783ef.png)

This is [the Beta version](https://clearcalcs.com/support/faqs/what-is-a-beta-template) of the Restrained Retaining Wall Calculator. We will continue to receive feedback for improvements, and the calculator will undergo external verification by a third-party engineering firm before being fully launched.

**Available on**: The Beta version is currently available for all users to test and share feedback. The calculator will be offered as part of the Pro plan at launch.

## Wood Shear Wall 

### Multi-Story Shear Wall enabled in Wood Shear Wall Calculator to AWC SDPWS 2021 and NDS 2018

By popular demand, we've now enabled the design of multi-story shear walls with the [Wood Shear Wall calculator](https://clearcalcs.com/calculations/timberShearWallASD).

You'll see that the location of the opening is set as identical on each floor by default. This indicates the panel ratio, which informs you whether the shear wall panel is engaged to distribute the loads and, therefore, whether you need chords designed for the shear wall.

[Watch the calculator in action](https://clearcalcs.wistia.com/medias/amy6t36o2r).

![calcsUS-woodshearwall-multi-story.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/calcs_US_woodshearwall_multi_story_15bbaeca20.png)

This new feature allows you to apply seismic or wind loads to each story separately. The calculator will either combine the same type of load or apply them individually. This also includes dynamically linking your multi-story shear walls to [multiple diaphragm analyses](https://clearcalcs.com/calculations/diaphragmAnalysis) for end-to-end shear wall design.

**Available on**: Wood Shear Wall Calculator is available for the Pro plan and above. 

## Timber Beam

### Sloped beams automatically considered in timber beam design to Australian Standard [AS 1720.1:2010](https://clearcalcs.com/standards/SA/AS-1720-1-2010-0)

If you're designing [timber beams in Australia](https://clearcalcs.com/calculations/timberComplexBeam), the presets for rafter and hip/valley (roof beams) now automatically consider the beam pitch when calculating the member length and forces. 

[Watch the calculator in action](https://clearcalcs.wistia.com/medias/g3e9u46d32).

You'll see an option to select whether you need a simple slope for your rafter or two different slopes for your hip/valley design. 

![calcsAU-timber-beam-incline.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/calcs_AU_timber_beam_incline_61eaaf95b1.png)

After that, you only need to input the horizontal length of the beam and the roof pitch to calculate your total length and forces. In the case of hip/valley, this means you can input two different incline angles based on your design.

![calcsAU-timber-beam-incline-input.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/calcs_AU_timber_beam_incline_input_fd0f27f1d8.png)

The calculator will then automatically calculate the loads and analyze the axial forces based on the beam incline. For hip/valley, this includes automatically calculating the triangular load as a result of  [the tributary area around the hip beam](https://clearcalcs.com/blog/what-is-load-and-tributary-width-in-structural-design-an-overview).

![calcsAU-timber-beam-incline-loads.png](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/calcs_AU_timber_beam_incline_loads_ba318ed07b.png)

## Resources

We've released new documentation for the Steel Beam Calculator to AISC 360-16. Read the documentation:
- [Worked example of steel beam design to AISC 360-16](https://clearcalcs.com/support/beams/design-example-continuous-beam-designed-per-aisc-360-16).
- [Interpreting and optimizing results for steel beam design to AISC 360-16](https://clearcalcs.com/support/beams/us-steel-beam-interpreting-optimizing-results).

## Take Action
Improve your structural workflow and accelerate your productivity by joining live events and meet others power users in the ClearCalcs community.

#### [Calculating Snow Loads Per IBC 2021](https://clearcalcs.com/webinars/snow-loads-ibc-2021)
Wednesday, August 30th, 1 pm (ET)

#### [Diaphragm Analysis and Lateral Load Linking for Shear Wall Design](https://clearcalcs.com/webinars/diaphragm-analysis)
Wednesday, September 27th, 1 pm (ET)

#### [Introduction to the Girder-Slab® System and Design Tool V3.4](https://clearcalcs.com/webinars/girder-slab-sytem-design)
Wednesday, October 11th, 1 pm (ET)

[Check out our upcoming webinars](https://clearcalcs.com/webinars) or [watch previous webinars](https://clearcalcs.com/webinars/archive) at your own pace!

-- 

That's all for this month. If you have any feature requests, you can send them to help@clearcalcs.com. Enjoy!


This month, we're introducing the release of Restrained (Basement) Retaining Wall, an update to Wood Shear Wall Calculator to include support for multi-story, and more. 


What's new at ClearCalcs? (August 2023)

Empty warehouse by PKM1 from Getty Images Signature via Canva

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[The complexities of portal frame design](https://clearcalcs.com/blog/portal-frames-types-and-design-considerations) can make the structural analysis and design process time-consuming for structural engineers. The “trick” is to leverage the capabilities of advanced Finite Element Analysis (FEA) software to optimize your structural analysis workflow.

In this article, we will explore the approach to analyzing portal frames with hand calculations and FEA-based software like [Portal Frame Analysis Wizard](https://clearcalcs.com/calculations/portalFrameAnalysis) to showcase how you can accomplish complex analyses in a matter of minutes, saving valuable time and resources. We will also review a number of innovative portal frame use cases in real-world [residential](https://clearcalcs.com/use-case/residential-design) and commercial projects.  

_For more resources on portal frame design, check out these other guides and resources:_
- _[Mastering Portal Frames: Types and Design Considerations](https://clearcalcs.com/blog/portal-frames-types-and-design-considerations)_
- _[How to Analyze a Portal Frame in ClearCalcs](https://support.clearcalcs.com/article/18-portal-frames)_
- _[Worked Example of Portal Frame Analysis in ClearCalcs](https://clearcalcs.com/support/analysis/portal-frame-analysis-worked-examples)_

## Introduction
The analysis of portal frames involves a series of steps to determine the internal forces and verify the structural stability. 

The process begins with load determination, where the applied loads are calculated based on the relevant standards and project-specific requirements. These loads are then used to assess the internal forces and bending moments within the frame.

Various methods can be employed for the analysis of portal frames. 
- The **moment distribution method** is a widely used hand calculation technique that allows for the evaluation of member forces and deflections. 
- However, with the advancements in technology, computer-aided structural analysis software has become increasingly popular. **Finite element method (FEM)** software enables more complex analysis, considering nonlinear behavior and precise modeling of materials and connections.

Tools like the [Portal Frame Analysis Wizard](https://clearcalcs.com/calculations/portalFrameAnalysis) calculator allow users to swiftly analyze single or multi-bay 2D portal frames in any material, saving significant time and effort. Whether it's a flat, gable, arch, or tied portal frame design, the calculator accommodates a variety of geometries, making it ideal for quick and straightforward designs. 

By simply providing the width, leg height, and loads, ClearCalcs automatically determines the necessary nodes and fixities, enabling a comprehensive finite element analysis encompassing moment, shear, axial loads, and displacement. 

## Design Example: Residential Portal Frame by Hand

Let's perform the actual numerical calculations for the residential portal frame design example, considering a clear span of 30 feet, a frame height of 12 feet, and a roof slope of 6:12.

### Step 1: Load Calculation

In this example, we will focus on wind loads which are typically critical in a portal frame design. 

Let's assume a wind speed of 120 mph and an exposure category of B.

Using the local building codes ([ASCE 7-22: Minimum Design Loads for Buildings and Other Structures](https://www.asce.org/publications-and-news/civil-engineering-source/article/2021/12/02/updated-asce-7-22-standard-now-available)), we determine the design wind pressure. 

Let's assume it to be 20 psf.

### Step 2: Internal Force Calculation

Assuming the wind load acts as a distributed load on the roof, we can calculate the internal forces within the portal frame.

The total wind load on the roof can be calculated as follows:
- Total Wind Load = Wind Pressure x Roof Area
- Total Wind Load = 20 psf x (30 ft x 15 ft) [assuming a triangular roof shape]
- Total Wind Load = 9000 lbs/ft

To calculate the bending moment at the base of the columns, we can assume equal distribution of the total wind load on both sides of the frame (note: a more detailed assessment would use the moment distribution method rather than making this assumption). 

Therefore, the bending moment at the base of each column is:
- Bending Moment = (Total Wind Load/2) x (30 ft/2)
- Bending Moment = 9000 lbs/ft x 15 ft
- Bending Moment = 135,000 ft-lbs

Note, external forces also need to be checked and these need to be considered across the tributary width (depth) of each bay.

### Step 3: Member Selection and Sizing

Based on the calculated bending moment, we need to select an appropriate steel section for the columns and beam.

Let's assume we select a W10x30 section for the columns. The properties of this section can be obtained from the [AISC steel manual](https://www.aisc.org/publications/steel-construction-manual-resources/).

For the beam, we can select a W12x35 section. Again, the properties of this section can be obtained from the[ AISC steel manual](https://www.aisc.org/publications/steel-construction-manual-resources/).

### Step 4: Stability Analysis

To ensure stability, we need to check the slenderness ratio of the columns. Let's assume the effective length of the columns is 12 feet (considering fixed supports at the top).

The slenderness ratio can be calculated using the formula:
- Slenderness Ratio = (Effective Length of Column) / (Radius of Gyration)
- Slenderness Ratio = 12 ft / 2.48 in (for W10x30 section) [Radius of Gyration obtained from AISC manual]

The AISC provides limits on the slenderness ratio, and if the calculated value exceeds these limits, additional bracing may be required.

### Step 5: Connection Design

For connection design, let's assume we use moment-resisting connections at the base of the columns. These connections provide additional stability and rigidity to the frame.

The design of moment-resisting connections involves checking the required connection capacities, such as shear capacity, moment capacity, and axial capacity, based on the design loads and selected steel sections. 

These calculations involve complex analysis and are beyond the scope of this example.

### Step 6: Verification and Review

Once the design calculations are completed, it is important to review and verify the design for compliance with US standards. This involves checking the adequacy of the selected sections, stability analysis, and overall structural integrity.

Software tools like ClearCalcs can assist in the verification process by performing automated checks based on the input parameters and design requirements.

Please note that the above calculations are simplified for demonstration purposes, and an actual design would require more comprehensive analysis and consideration of various factors.

## Design Example: Residential Portal Frame Using ClearCalcs

For a complete and accurate design it is recommended that engineers use software like the Portal Frame Analysis Wizard calculator. 

Let’s work through an example where there is 1 bay that has a width of 30 feet. The leg heights are both 12 feet. The apex is 15 feet from the left leg and is 19.5 feet from the base. The portal frames use W12X35 members. 

![Single bay gable portal frame](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_example_portal_frames_7c4db182eb.png)

There is 20plf of distributed load on the vertical chords, the chords perpendicular to the member, and also 20plf inward distributed load on the left leg.

### Step 1: Input Portal Frame Geometry
All the parameters for the portal frame geometry are input from the sketch above.

![Key properties input in ClearCalcs portal frame analysis wizard](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_example_portal_frames_inputs_cd16402ef0.png)

Typically they are specified by the architect and are restricted by land boundaries (bay width) or local building height requirements (leg height, height of apex). 

Most portal frames are single gables, but there can be other types as detailed in the article [Mastering Portal Frames: Types and Design Considerations](https://clearcalcs.com/blog/portal-frames-types-and-design-considerations). 

### Step 2: Member Selection
ClearCalcs has an in-built member selection tool that has standard hot-rolled steel, cold-formed steel, and timber sections built in to speed up the design process and ensure that the members that are specified in the design can be procured by the builders.

![Member selection for steel, cold-formed steel and timber in ClearCalcs portal frames analysis wizard](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_example_portal_frames_member_selection_8e62b3a40f.png)

### Step 3: Input Loads
Our example calls for 20plf of distributed load on the vertical chords, the chords perpendicular to the member, and also 20plf inward distributed load on the left leg. 

![Input for distributed loads in ClearCalcs portal frames analysis wizard](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_example_portal_frames_distributed_loads_5adfad37c4.png)

Point loads can also be input but are not applicable to our example.

### Step 4: Summary Results
ClearCalcs summarises the key actions on the system as per the below tables. 

![Summary of reactions on portal frame members in ClearCalcs portal frames analysis wizard](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_example_portal_frames_summary_outputs_a75220f05f.png)

ClearCalcs also provides a graphical representation of the bending moment, shear force, axial load, extension, displacement, and reaction forces at all points along the portal frame, which is incredibly difficult to do by hand and helps to understand the behavior of the structure under the applied loads.

![Bending moment, shear force, axial load, extension, displacement, and reaction forces diagrams in ClearCalcs portal frame analysis wizard](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_example_portal_frames_diagrams_19826ce3a3.png)

Users can then complete their Portal Frame member design using these outputs and inputting them into the Member (Design Only) calculator such as the [wood member design calculator](https://clearcalcs.com/new/sheet/TemplateCode=timberMemberASD&presetCode=elementLink
) or the [steel member design calculator](https://clearcalcs.com/new/sheet/tTemplateCode=steelMemberASD&presetCode=elementLink).

[See it in action](https://www.loom.com/share/81ac6ec11fc14ac1b6f7c51a868de3fa?sid=469c4b94-e8f0-4105-b090-3f0aa4c50dff).

## Key Challenges in Portal Frame Analysis

Portal frame analysis presents challenges that [structural engineers](https://clearcalcs.com/persona/structural-engineer), [architects](https://clearcalcs.com/persona/architect), and [building designers](https://clearcalcs.com/persona/building-designer) must address. Some common challenges specific to portal frame analysis include:

### Geometric Nonlinearity

Portal frames often experience large deformations and displacements, especially under [lateral loads](https://clearcalcs.com/blog/load-transfer-in-residential-structures-from-roof-to-foundation). 

Analyzing and accounting for geometric nonlinearity can be challenging, as it requires considering the changing shape and stiffness of the structure as it deforms. Nonlinear analysis methods, such as the finite element method (FEM), may be necessary to accurately capture the behavior of the frame.

### Member Axial-Bending Interaction

Portal frame members, such as columns and beams, often undergo both axial forces (compression or tension) and bending moments simultaneously. The interaction between these axial and bending forces can affect the behavior and capacity of the members. 

Accurately capturing and analyzing this interaction is crucial for the overall stability and strength of the portal frame.

### Connection Behavior

Connections between portal frame members play a significant role in load transfer and overall frame performance. The behavior of moment-resisting connections, such as bolted or welded connections, can be complex and challenging to model accurately. 

It is important to consider connection stiffness, strength, and rotational capacity when analyzing the frame.

### Lateral Load Distribution

Portal frames are designed to resist lateral loads, such as [wind](https://clearcalcs.com/calculations/loadsWindCnCASCE7-16) or [seismic](https://clearcalcs.com/calculations/seismicAnalysisUS) forces. However, distributing these lateral loads across the frame can be challenging due to the frame's inherent stiffness and moment-resisting characteristics. 

Analyzing and ensuring that the loads are adequately distributed to each member and connection is crucial for a structurally sound design.

### Dynamic Effect

In certain cases, portal frames may be subject to dynamic loads, such as vibrations from equipment or machinery within the building. Analyzing the dynamic response of the frame and assessing its impact on the structural performance requires specialized analysis techniques, such as modal analysis or response spectrum analysis.

### Second-Order Effects

Portal frames are susceptible to second-order effects, which arise from the interaction between member deformations and structural stiffness. These effects can lead to additional moments and displacements that need to be accounted for in the analysis. 

Neglecting second-order effects can result in an inaccurate assessment of the frame's behavior and capacity.

### Construction Sequence and Temporary Loads

Portal frames are often erected in a staged construction process, with temporary loads applied during construction. Analyzing the frame's behavior under temporary loads and considering the effects of construction sequence and erection methods are crucial for ensuring stability and safety during the construction phase.

## Real-Life Design Examples and Case Studies

### Residential Project: Green Hills Residence

The Green Hills Residence is a prime example of innovative portal frame design in a residential project. The design team aimed to create a spacious and visually appealing living space while ensuring structural efficiency.

![An example of residential project using portal frames](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_example_green_hills_residence_35e2fdb7a8.png)
_Figure 1: An example of residential projects utilising portal frames ([Image Credit](https://mariaproperti.co.id/listings/green-hills-residence/))_

In this project, the portal frame design allowed for a large open living area with minimal interior columns, providing flexibility for interior layout and aesthetics. The frame was designed to withstand both wind and seismic loads as per the local building codes.

To achieve structural efficiency, the design team opted for a hybrid construction approach using a combination of steel portal frames and lightweight timber infill walls. This combination allowed for optimal utilization of materials, reducing construction costs while maintaining structural integrity.

The portal frames were designed using advanced analysis software, considering load combinations, member sizing, and stability analysis. The result was a durable and efficient structure that met the requirements of the residential project while showcasing innovative design approaches.

### Light Commercial Project: Industrial Warehouse

The design of an industrial warehouse often requires large clear spans and high load-carrying capacities. Portal frames offer an ideal solution for such projects, enabling efficient use of space and structural stability.

In a recent industrial warehouse project, a portal frame design was employed to achieve the desired functional requirements while optimizing structural efficiency. The project involved a clear span of 60 feet and a height of 20 feet.

![An example of light commercial project utilizing portal frames](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_examples_commercial_shed_91b7eb8ff9.jpg)
_Figure 2: An example of an industrial project using portal frames ([Image Credit](https://www.allaboutsheds.com.au/blog/what-is-a-portal-frame/))_

To ensure structural integrity, the portal frames were designed using high-strength steel sections with moment-resisting connections at the base. The frames were subjected to rigorous analysis considering wind loads, seismic loads, and live loads as per the applicable building codes.

To enhance material efficiency, the design team utilized the concept of tapered portal frames. By varying the section sizes along the height of the frame, excess material usage was minimized while maintaining the required strength and stiffness.

The successful completion of this light commercial project demonstrated the application of portal frame design principles in achieving optimal structural efficiency, load-carrying capacity, and cost-effectiveness.

### Mixed-Use Project: Harbour Plaza

Harbour Plaza is a mixed-use development that seamlessly integrates residential and light commercial spaces. The design concept called for an open and inviting layout, and portal frames played a significant role in realizing this vision.

<img src="https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_worked_examples_harbour_plaza_3c6b9bfbd0.jpg" height="500px">

_Figure 3: An example of mixed use development project utilizing portal frames ([Image Credit](https://www.tripadvisor.com/Hotel_Review-g294217-d302331-Reviews-Harbour_Plaza_North_Point-Hong_Kong.html))_

In this project, portal frames were used to create expansive storefront areas for shops and restaurants on the ground floor. The frames provided ample natural light and unobstructed views, enhancing the overall aesthetics of the building.

To ensure the structural stability and safety of the portal frames, wind loads and seismic loads were carefully considered during the design phase. The frames were designed with moment-resisting connections and suitable steel sections to withstand the applied loads.

In terms of material choices, the design team prioritized sustainability and opted for high-performance steel with recycled content. This allowed for a reduced environmental footprint while maintaining structural integrity and durability.

The successful completion of Harbour Plaza highlighted the versatility of portal frames in mixed-use projects, offering both structural efficiency and architectural appeal.

## Conclusion

The complexities of portal frame design have traditionally made the structural analysis and design process time-consuming for engineers. However, with advanced FEA-based software, engineers can optimize their workflow, achieve complex analyses in less time, and save valuable resources to develop more innovative projects. 

_For more resources on portal frame design, check out these other guides and resources:_
- _[Mastering Portal Frames: Types and Design Considerations](https://clearcalcs.com/blog/portal-frames-types-and-design-considerations)_
- _[How to Analyze a Portal Frame in ClearCalcs](https://support.clearcalcs.com/article/18-portal-frames)_
- _[Worked Example of Portal Frame Analysis in ClearCalcs](https://clearcalcs.com/support/analysis/portal-frame-analysis-worked-examples)_

_Disclaimer: The case studies mentioned in the article is solely based on the personal experience of the writer. Due to confidentiality we are unable to provide more specific details or links related to the project._

In this article, we will explore the approach to analyzing portal frames with hand calculations and FEA-based software like ClearCalcs’ Portal Frame Analysis Wizard to showcase how you can accomplish complex analyses in a matter of minutes, saving valuable time and resources. 

Structural Analysis of Portal Frames: Worked Examples and Case Studies

An example of steel portal frame structure from Getty Images via Canva

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Portal frames play a crucial role in the construction of [residential](https://clearcalcs.com/use-case/residential-design) and light commercial projects, providing a reliable and cost-effective solution for transferring vertical and lateral loads in buildings. 

These structural systems are widely used due to their versatility and ability to span large distances without the need for interior columns. 

This article will explore the basics of portal frame structure design, including the different types, factors we need to consider in the design phase, and the applicable codes and standards in the United States.

_For more resources on portal frame design, check out these other guides and resources:_ 
- _[Structural Analysis of Portal Frames: Worked Examples and Case Studies](https://clearcalcs.com/blog/portal-frames-worked-examples-and-case-studies)_
- _[How to Analyze a Portal Frame in ClearCalcs](https://support.clearcalcs.com/article/18-portal-frames)_
- _[Worked Example of Portal Frame Analysis in ClearCalcs](https://clearcalcs.com/support/analysis/portal-frame-analysis-worked-examples)_

## Introduction

Portal frames consist of two vertical columns connected by a horizontal or sloped beam at the top, forming a rigid rectangular or trapezoidal shape. The beam acts as a portal, distributing the loads to the columns typically through bolted end plate connections, providing overall stability to the structure. The columns are usually fixed at their bases and may include moment-resisting connections. 

Portal frames offer numerous benefits, making them a popular choice in the construction industry. Advantages of portal frames include:
- They provide open and flexible spaces, allowing for expansive floor plans and easy customization. 
- The absence of interior columns maximizes the usable area within a building, enabling more efficient utilization of space. 
- Provided that the design considerations are observed, portal frame can offer excellent structural performance, stability, and resistance to lateral loads, such as wind and seismic forces.

## Types of Portal Frames

Portal frames can be categorized into different types based on the shape and arrangement of their members. Here are some of the different types of portal frames commonly employed in residential and light commercial projects:

### Single-Span Portal Frame 
The single-span portal frame is the simplest and most common type. It consists of a rigid frame with two columns and a horizontal or sloped beam spanning between them. This frame provides a clear span between the columns, offering flexibility in interior space planning. 

It is often used in residential garages, small warehouses, and workshops.

### Multi-Span Portal Frame 
The multi-span portal frame consists of multiple single-span frames connected together with intermediate columns and beams. This type of frame is used when a larger clear span is required, exceeding the capacity of a single-span frame. 

Multi-span portal frames are suitable for light commercial buildings, such as retail spaces, showrooms, and small-scale industrial structures.

![A diagram showing different types of portal frames based on the number of spans](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_portal_frames_types_span_99b8c32428.jpg)
_Figure 1 Types of portal frames based on their number of spans ([Reference](https://havitsteelstructure.com/steel-frame-building/))_

### Tapered Portal Frame 

Tapered portal frames are designed with beams and columns of variable sections along the height. The sections gradually decrease in size from the base to the ridge, which ensures the rafters have a larger section area at the locations of the maximum bending moment to maximize efficiency. 

Tapered frames are also commonly used in architectural applications where aesthetic considerations are important, such as entry canopies, covered walkways, and grand entrances.

![An image showing an example of tapered portal frames](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_tapered_portal_frames_5ab1e80f0d.jpg)
_Figure 2: An example of tapered portal frames ([Reference](https://www.cecobuildings.com/blog/primary-building-frame-systems/))_

### Curved Portal Frame 

Curved portal frames are designed with a curved horizontal beam instead of a straight one. This frame type adds architectural interest and visual appeal to residential and light commercial projects. 

Curved portal frames can be used in applications like atriums, roof canopies, and architectural features where a distinctive curved form is desired.

![An image showing an example of curved portal frames](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_curved_rafters_portal_frames_fc526c2091.jpg)
_Figure 3: Curved rafters in a curved portal frame ([Reference](https://structville.com/2021/09/structural-design-of-curved-rafters.html))_

### Lean-To Portal Frame 

A lean-to portal frame consists of a single sloping roof supported by a primary portal frame structure. It is commonly used as an extension or annex to an existing building, providing additional space. 

Lean-to frames are often utilized in residential projects for extending living areas, adding carports or covered patios, and creating storage spaces.

![An image showing an example of lean-to-portal-frames](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_lean_to_portal_frames_ede05b68ed.jpg)
_Figure 4: An example of lean-to portal frame ([Reference](https://source.thenbs.com/product/fabricated-lean-to-portal-frame/wA7aXsjw3sS4AcEdZCucDM/9zrim6d6pPtfQiMeuzWdRN))_

### Canopy Portal Frame 

Canopy portal frames are designed specifically to create covered outdoor areas. They feature a single-span frame with a horizontal beam that extends beyond the columns to provide shelter. 

Canopy portal frames are commonly used in residential projects to create covered porches, carports, and outdoor living spaces.

![An image showing an example of canopy portal frames](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_canopy_portal_frames_039ebefc62.jpg)
_Figure 5: An example of canopy portal frames ([Reference](https://www.hindawi.com/journals/ace/2019/9047679/))_ 

### Truss Portal Frame 

Trusses can be utilized in the rafters and ridge of a portal frame to achieve the largest spans of any type of portal frame. 

They are typically utilized in commercial warehouses.

![An image showing an example of truss portal frames](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_truss_portal_frames_ee666a88fc.webp)
_Figure 6: An example of truss portal frames ([Reference](https://blog.swantonweld.com/key-components-of-steel-buildings))_

## Applicable Codes & Standards

In the United States, portal frame design is governed by various [standards](https://clearcalcs.com/standards) to ensure the safety and performance of structures. The [American Institute of Steel Construction (AISC)](https://www.aisc.org/) standards, in conjunction with the [International Building Code (IBC)](https://www.iccsafe.org/products-and-services/i-codes/2018-i-codes/ibc) and [American Society of Civil Engineers (ASCE)](https://www.asce.org/) guidelines, form the basis for portal frame design in residential and light commercial projects. 

Adhering to these standards is crucial for [structural engineers](https://clearcalcs.com/persona/structural-engineer), [architects](https://clearcalcs.com/persona/architect), and [building designers](https://clearcalcs.com/persona/building-designer) to ensure the integrity and safety of the buildings they create. 

Here are the key considerations outlined in the AISC standards for portal frame design:

### Load Combinations

The AISC standards provide specific load factors to consider for various types of loads, including dead loads, live loads, [wind loads](https://clearcalcs.com/calculations/loadsWindCnCASCE7-16), and [seismic loads](https://clearcalcs.com/calculations/seismicAnalysisUS). The load factor design methodology is covered in Chapter B of [AISC 360-16](https://www.steel.org.au/resources/elibrary/library/ansi-aisc-360-16-specification-for-structural-steel-buildings/).

These load factors account for uncertainties and variations in load magnitudes to ensure the structure can safely support the intended loads.

### Material Properties 

The properties of various steel materials, including their mechanical properties, are typically covered in Chapter A and Appendix B of the AISC Steel Construction Manual. The AISC standards specify the material properties of structural steel, such as yield strength, tensile strength, and elasticity modulus. 

These properties determine the strength and behavior of the steel members in the portal frame. Designers must select appropriate steel sections that meet the required load-carrying capacities and structural performance criteria.

### Design Methodologies 

The AISC standards outline different design methodologies for portal frames, including the Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD) methods. The design methodologies for portal frames can be found in Part 2  of the 15th edition of the AISC Steel Construction Manual. This chapter provides information on different design approaches and methods.

The ASD method allows for a direct comparison of applied loads to the allowable stresses in the members. In contrast, the LRFD method considers load and resistance factors to determine the required member capacities. 

Designers must choose the appropriate method based on project requirements and code provisions.

### Stability Analysis 

Stability is a critical aspect of a portal frame design. The AISC standards provide guidelines for stability analysis, including evaluating the slenderness ratio, effective length, and bracing requirements for columns and beams. The stability analysis of portal frames, including the evaluation of buckling and lateral-torsional buckling, is covered in Part 3 and Part 13 of the AISC Steel Construction Manual.

Designers must ensure that the portal frame components are adequately braced to resist lateral forces, such as wind and seismic loads, and prevent buckling or instability.

### Connection Design 

The AISC standards provide detailed guidelines for designing moment-resisting connections in portal frames. nformation on connection design, including the design of moment connections, bolted connections, and welded connections, can be found in Chapter 10 of the AISC Steel Construction Manual.

These connections are crucial for transferring loads and moments between the beams and columns. 
Designers must consider factors such as connection capacity, shear resistance, moment transfer, and bolt design to ensure reliable and efficient connection performance.

### Construction Tolerances 

The AISC standards also address construction tolerances for portal frame members and connections. 
These tolerances ensure proper fit-up during fabrication and construction, minimizing alignment issues and potential structural deficiencies. 

Designers should specify appropriate tolerances to maintain the structural integrity of the portal frame during the construction process. Guidelines and recommendations for construction tolerances can be found in Chapter 6 of the AISC Steel Construction Manual.

## Design Considerations

During the design phase, several factors must be carefully considered to ensure the structural integrity of portal frames:

### Load Calculations

Accurate load calculations are essential for a portal frame design. Considerations include dead loads (weight of the structure itself), live loads (occupant and equipment loads), wind loads, seismic loads, and any other relevant loads specific to the project. 

Adhering to local building codes and standards is crucial when determining the magnitudes and combinations of these loads.

### Load Combinations

Combining different types of loads is vital to accurately assess the portal frame's structural response. [Load combinations](https://clearcalcs.com/blog/building-codes-and-load-combinations-in-the-united-states) involve considering the simultaneous effects of multiple loads, such as dead load with live load, wind load, or seismic load. 

Combinations should be determined in accordance with applicable design codes, such as the International Building Code (IBC) in the United States.

### Material Selection

[Choosing the appropriate material](https://clearcalcs.com/support/advanced-tips-and-tricks/quickly-finding-the-best-section-with-the-member-suggestor) for portal frames is critical. Structural steel is commonly used due to its high strength-to-weight ratio and versatility. 

The material selection should consider factors such as the required load-carrying capacity, environmental conditions (corrosion resistance), and architectural considerations. Other materials, such as reinforced concrete or timber, may be used for specific applications.

### Structural Stability

Ensuring the stability of portal frames is crucial for their performance. Stability considerations include assessing the frame's resistance against buckling, lateral-torsional stability of beams, and stability of columns. Bracing systems, moment connections, and appropriate member sizing are key aspects of maintaining stability. 

The outputs of the portal frame analysis wizard can be input into software design tools ClearCalcs calculators to detail the design of the portal frame. ClearCalcs can be utilised for the bracing system design (which often use steel beams) and the rafter design using the steel beam calculator. The moment connections can be designed by iteration using the steel bolt connection and welded connection calculators. The stability of the columns can be assessed using ClearCalcs’ steel column calculator.


### Connection Design

The design of connections between beams and columns is critical to portal frames' overall performance and strength. 

Moment-resisting connections, such as bolted or welded connections, are commonly used to transfer loads and moments between members. 

The design should consider the required connection capacity, shear resistance, moment transfer, and compatibility with the chosen material.

### Deflection and Serviceability

Portal frames must be designed to meet serviceability requirements, which include controlling deflections and vibrations. 

Excessive deflections can impact the functionality of the structure and its aesthetic appearance. Designers should consider deflection criteria provided by relevant codes and standards to ensure occupant comfort and structural performance.

Tools like [Portal Frame Analysis Wizard](https://clearcalcs.com/calculations/portalFrameAnalysis) allows you to perform quick FEA analysis of a 2D portal frame to determine deflection for simple and common applications. 

![Deflection diagram for portal frame analysis in ClearCalcs](https://clearcalcs-prod2-cms.s3.amazonaws.com/BLOG_deflection_diagram_portal_frame_analysis_71175a58a9.png)\
_Figure 7: Deflection diagram for Portal Frame Analysis in ClearCalcs ([Reference](https://clearcalcs.com/support/analysis/portal-frames))_

### Architectural Integration

Portal frames often play a prominent role in the architectural aesthetics of a building. Design considerations should consider the desired architectural features, such as the shape, height, and proportions of the frame. 

Integration with other building elements, such as cladding systems and architectural finishes, should also be considered.

### Constructability and Cost-Efficiency

Designing portal frames that are constructible and cost-efficient is important. Considering factors such as standard sizes of steel sections, ease of fabrication and erection, and minimizing waste can contribute to a more economical design.

## Conclusion

In conclusion, mastering portal frames design involves understanding their types, design considerations, and compliance with applicable building standards and codes. Portal frames offer versatile and cost-effective solutions for residential and light commercial projects, providing open and flexible spaces while maximizing usable area. 

_For more resources on portal frame design, check out these other guides and resources:_ 
- _[Structural Analysis of Portal Frames: Worked Examples and Case Studies](https://clearcalcs.com/blog/portal-frames-worked-examples-and-case-studies)_
- _[How to Analyze a Portal Frame in ClearCalcs](https://support.clearcalcs.com/article/18-portal-frames)_
- _[Worked Example of Portal Frame Analysis in ClearCalcs](https://clearcalcs.com/support/analysis/portal-frame-analysis-worked-examples)_

This article will explore the basics of portal frame structure design, including the different types, factors we need to consider in the design phase, and the applicable codes and standards in the United States.

Mastering Portal Frames: Types and Design Considerations

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In this article, we will explore the definition, function, and various types of roof rafters, including their unique features and applications. We will also discuss different materials used for rafters, such as wood, steel, and cold-formed steel, along with practical tips for rafter design and analysis.

Practical Guide for Design and Analysis of Roof Rafters

Multi level retaining walls with plants in the backyard by zstockphotos by Getty Images from Canva 

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## Introduction

Retaining walls play a crucial role in providing stability and support to landscapes, especially in [residential](https://clearcalcs.com/use-case/residential-design) and light commercial projects. These structures are designed to hold back soil and prevent erosion, creating usable space and enhancing the aesthetics of the surroundings. In this guide, we will explore various types of retaining walls commonly used in such projects, highlighting their advantages, disadvantages, design considerations, cost factors, and construction methodologies.

The different types of retaining walls covered in this guide are gravity walls, [cantilever walls](https://clearcalcs.com/calculations/retainingWallCantileverUSAACI318-19), sheet pile walls, anchored walls, and segmental retaining walls. Each type offers unique characteristics and is suitable for specific applications based on factors such as soil conditions, site requirements, and budget constraints.

By understanding the characteristics and considerations of each type of retaining wall, you can make informed decisions when planning and executing your residential or light commercial project. Whether you're looking for a cost-effective solution, increased design flexibility, or the ability to handle challenging soil conditions, this guide will provide valuable insights to help you choose the right retaining wall for your specific needs.

![Illustrations of different types of retaining walls](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/BLOG_retaining_wall_types_290c9f742a.jpg)
_Figure 1: Types of Retaining Walls and Their Forces ([Reference](https://en.wikipedia.org/wiki/Retaining_wall))_

## Gravity Walls

### Advantages
- Simple design and construction process.
- Cost-effective for shorter wall heights.
- Suitable for a wide range of soil conditions.
- Can be constructed using a variety of materials, such as concrete, stone, or brick.

### Disadvantages
- Limited to lower wall heights (typically up to 10-15 feet).
- Requires a sufficient footprint and proper drainage to resist soil pressure.
- May not be suitable for sites with poor soil conditions or high surcharge loads.

### Design Considerations
- Stability against lateral soil pressure.
- Adequate drainage and backfill compaction should be considered to prevent water buildup and potential wall movement.
- Material selection based on desired aesthetic

### Cost Considerations
- Cost-effective for shorter wall heights and simple designs.
- Material costs vary depending on the chosen material (concrete, stone, brick, etc.).
- Simplicity of the design leads to faster execution reducing construction costs.

### Construction Methodology
- Excavate the area and prepare a leveled foundation.
- Construct a concrete footing at the base of the wall.
- Build the wall using concrete, stone, or brick materials, ensuring proper alignment and leveling.
- Backfill the space behind the wall with suitable material, compacting it in layers to ensure stability.
- Install drainage features such as weep holes or perforated pipes to prevent water buildup

## Cantilever Walls

### Advantages
- Suitable for medium to high wall heights (up to 25-30 feet).
- Requires a smaller footprint compared to gravity walls.
- Can be constructed using various materials, such as concrete or steel.
- Offers more design flexibility and aesthetic options.

### Disadvantages
- Design and construction can be more complex than gravity walls.
- Requires careful consideration of soil properties, loads, and structural stability.
- Higher construction costs compared to gravity walls.

### Design Considerations
- Thorough analysis of loads and soil conditions to determine proper wall dimensions and reinforcement and foundation requirements.
- Selection of suitable materials and construction techniques based on the project requirements and desired aesthetic

### Cost Considerations
- Higher construction costs compared to gravity walls due to their more complex design and reinforcement requirements.
- Costs can increase with higher wall heights and intricate designs.

### Construction Methodology
- Excavate and construct a concrete footing with appropriate dimensions and reinforcement.
- Install formwork to shape the wall and place reinforcement according to the design.
- Pour concrete into the formwork, ensuring proper consolidation and vibration to eliminate voids.Allow the concrete to cure, then remove the formwork.
- Backfill behind the wall, compacting the soil in layers for stability.
- Incorporate drainage elements to prevent water pressure against the wall.

## Sheet Pile Walls

### Advantages
- Effective for projects with limited space and high water table conditions.
- Can be installed in various soil types, including soft or cohesive soils.
- Suitable for temporary or permanent applications.
- Quick installation.

### Disadvantages
- Limited to certain wall heights (typically up to 25-30 feet).
- May require additional protection against corrosion or damage in certain environments.
- May not be suitable for sites with dense or rocky soils.
- Poor aesthetic appeal.

### Design Considerations
- Proper analysis of soil conditions, water table, and required wall embedment depth.
- Selection of suitable sheet pile material (steel, vinyl, fiberglass, etc.) based on project-specific requirements.
- Consideration of corrosion protection measures if needed.

### Cost Considerations
- Sheet pile walls can vary in cost depending on factors such as wall height, material type, and installation method.
- Installation costs can be relatively lower due to the quick installation process.

### Construction Methodology
- Drive or vibrate sheet piles into the ground to the desired depth, ensuring proper alignment and interlocking.
- Anchor the sheet piles if required for additional stability.
- Backfill the space behind the sheet piles, compacting the soil to provide support.
- Install tiebacks or bracing as necessary to resist lateral forces.
- Ensure proper connection and alignment of the sheet piles.

## Anchored Walls

### Advantages
- Suitable for tall retaining walls (exceeding 25-30 feet) or sites with limited space.
- Provides increased stability through the use of anchors or tiebacks.

### Disadvantages
- Requires specialized design and construction techniques.
- Higher construction costs compared to other wall types.
- Anchoring systems may require periodic maintenance.

### Design Considerations
- Thorough analysis of soil conditions, loads, and lateral forces to determine the number and spacing of anchors or tiebacks.
- Selection of appropriate anchor materials (such as soil nails, ground anchors, or rock anchors) based on the site conditions and design requirements.
- Consideration of potential limitations and constraints in installing and maintaining the anchoring system.

### Cost Considerations
- Anchored walls generally have higher construction costs due to the complexity of the design and the installation of anchoring systems.
- Costs vary based on factors such as wall height, number of anchors, anchor materials, and labor requirements.

### Construction Methodology
- Excavate and construct a concrete footing to support the wall.
- Install anchor elements such as soil nails, ground anchors, or rock anchors according to the design.
- Build the wall, incorporating the necessary reinforcement and ensuring proper connection with the anchor elements.
- Backfill behind the wall, compacting the soil for stability.
- Install tiebacks or tension the anchors to resist lateral forces.
- Incorporate drainage features to prevent water accumulation.

## Segmental Retaining Walls

### Advantages
- Offers design flexibility and aesthetic appeal with various textures, colors, and shapes available.
- Quick and efficient installation process.
- Suitable for a wide range of wall heights and soil conditions.
- Can be used for both straight and curved walls.

### Disadvantages
- Limited to certain wall heights (typically up to 15-30 feet).
- Requires proper compaction and backfilling to ensure stability.
- Segmental retaining walls may require periodic maintenance and repair.

### Design Considerations
- Thorough analysis of soil conditions, loads, and reinforcement requirements.
- Selection of appropriate block size, shape, and connection methods based on project-specific requirements.
- Proper consideration of proper drainage and compaction during construction.

### Cost Considerations
- Segmental retaining walls can vary in cost depending on factors such as wall height, block materials (concrete, stone), and design complexity.
- Construction costs are generally moderate due to the efficiency of the installation process.

### Construction Methodology
- Prepare the foundation by leveling the base and providing suitable compaction.
- Place interlocking segmental blocks, ensuring proper alignment and leveling.
- Install geogrid reinforcement layers as necessary for stability.
- Backfill the space behind the wall, compacting the soil in layers.
- Ensure proper drainage by incorporating drainage features.

## Conclusion

Retaining walls are essential elements in residential and light commercial projects, providing structural integrity, erosion control, and aesthetic appeal to the landscape. Throughout this guide, we have explored the advantages, disadvantages, design considerations, cost factors, and construction methodologies of various types of retaining walls.

Gravity walls offer simplicity and cost-effectiveness for shorter wall heights, while cantilever walls provide greater design flexibility and suitability for medium to high wall heights. Sheet pile walls excel in limited space and high water table conditions, while anchored walls offer stability for tall walls or constrained sites. Segmental retaining walls combine design flexibility with ease of installation.

By following proper design and construction practices, including adequate drainage, suitable backfilling, and necessary reinforcements, you can maximize the effectiveness and longevity of your retaining wall. It is also important to consider periodic maintenance and potential repair requirements for certain wall types.

_[To learn more about structural design considerations for retaining walls and industry best practices, check out this article.](https://clearcalcs.com/blog/retaining-wall-design-us)_

In this guide, we will explore various types of retaining walls commonly used in residential and light commercial projects, highlighting their advantages, disadvantages, design considerations, cost factors, and construction methodologies.

Types of Retaining Wall for Residential and Light Commercial Projects

An image showing a garden retaining wall 

small_[BLOG] cantilever-retaining-wall.png

thumbnail_[BLOG] cantilever-retaining-wall.png

[BLOG] cantilever-retaining-wall.png

This comprehensive guide aims to assist structural engineers, building designers, and architects in the United States by focusing on American standards and key structural considerations for retaining wall design.

Retaining Wall Design to American Standards: Structural Considerations

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## Introduction 

In the ever-evolving construction industry, new materials and techniques are constantly being introduced to meet the demand for sustainable and efficient building solutions. One such material that has gained significant popularity in recent years is cold-formed steel. 

This article serves as a comprehensive guide for structural engineers who are interested in using cold-formed steel as a structural material in residential and light commercial projects. We will explore what cold-formed steel is, its benefits, its applications in building construction, and key considerations for engineers

## What is Cold-Rolled Steel?

Cold-formed steel refers to steel products that are formed by cold-working processes, such as rolling or pressing, at room temperature. 

Unlike hot-rolled steel, which is shaped while it is heated, cold-formed steel is manufactured at lower temperatures, resulting in distinct mechanical properties. 

Cold-formed steel exhibits excellent strength-to-weight ratio, dimensional stability, and uniformity in shape and size. These properties make it an attractive choice for a wide range of applications in the construction industry, and it has become particularly popular as a framing choice in residential builds.

![Cold-Formed Steel Construction from https://www.ispansystems.com/news/cost-comparison-cold-formed-steel-concrete-wood/](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Cold_Formed_Steel_5526d0d3ce.jpg)
_Figure 1: Example of cold-formed steel in residential & light commercial projects ([Reference](https://www.ispansystems.com/news/cost-comparison-cold-formed-steel-concrete-wood/))_

## Cold-Formed Steel as a Building Material

Cold-formed steel offers numerous benefits as a construction material. 

Firstly, it is highly durable and resistant to corrosion, ensuring long-term structural integrity. 

Secondly, cold-formed steel possesses higher strength, fire resistance, dimensional stability and is lighter than hot rolled steel and timber, allowing for the creation of lightweight structures permitting longer spans without compromising on load-bearing capabilities. 

### Comparison Between Cold-Formed Steel vs. Hot-Rolled Steel

The different manufacturing procedures between cold-formed steel and hot-rolled steel are summarised quite succinctly in[ this video](https://www.youtube.com/watch?v=OBG7Y5_Cf_s) as well as a high-level overview of the key differences between the two steel types in the below comparison.

#### Cold-Formed Steel

- **Manufacturing Process:** Cold-Working
- **Mechanical Properties:** High Strength
- **Corrosion Resistance:** Excellent
- **Dimensional Stability:** High
- **Fire Resistance:** High
- **Design Flexibility:** High
- **Weight:** Lighter
- **Sustainability:** Recyclable
- **Price:** More Expensive
- **US Design Standards:** American Iron and Steel Institute (AISI) S100 - "North American Specification for the Design of Cold-Formed Steel Structural Members."
- **Australian Design Standards:** [AS/NZS 4600 - Cold-formed steel structures.](https://clearcalcs.com/standards/SA/AS-NZS-4600-2018-0)

#### Hot-Rolled Steel

- **Manufacturing Process:** Hot-Working
- **Mechanical Properties:** High Ductility
- **Corrosion Resistance:** Moderate
- **Dimensional Stability:** Moderate
- **Fire Resistance:** Moderate
- **Design Flexibility:** Moderate
- **Weight:** Heavier
- **Sustainability:** Recyclable
- **Price:** Less Expensive
- **US Design Standards:** [American Institute of Steel Construction (AISC) 360 - Specification for Structural Steel Buildings.](https://www.steel.org.au/resources/elibrary/library/ansi-aisc-360-16-specification-for-structural-steel-buildings/)
- **Australian Design Standards:** [AS 4100:2020 - Steel structures](https://clearcalcs.com/standards/SA/AS-4100-2020-0)

## Cold-Formed Steel Framing

One of the primary applications of cold-formed steel in construction is framing. 

### Steel vs. Timber Framing

Cold-formed steel framing offers several advantages over traditional wood framing. It provides enhanced structural stability, as the material's consistent properties and uniformity eliminate common issues such as warping, splitting, or shrinking. 

Moreover, cold-formed steel framing allows for greater design flexibility, facilitating the creation of complex architectural shapes and configurations that aren’t achievable with timber due to its rigid material properties. 

While supply lead times and cost are the most critical factors in determining the choice of framing (which can be considered by contacting local framing suppliers), the below section can help a structural engineer choose between timber and steel framing.

### Timber Framing

#### Advantages of Timber Framing

1.  **Sustainability**: Timber is a renewable resource and has a lower carbon footprint compared to steel. 
2.  **Insulation**: Timber has natural insulating properties, providing better thermal performance and reducing energy consumption.
3.  **Aesthetics**: Timber framing provides a warm and traditional look that many homeowners find appealing. 
4.  **Cost-effectiveness**: Timber framing is often less expensive than steel framing, especially for smaller residential projects which can be stick-built on site.
5.  **Ease of construction**: Timber frames are lightweight and easier to handle, making them more suitable for DIY projects or remote locations.

### Disadvantages of Timber Framing

1. **Vulnerability to pests**: Wood can be susceptible to termite and rot damage if not properly treated and maintained.
2. **Limited span capabilities**: Timber frames may require additional supports or columns for larger open spaces compared to steel frames.
3. **Fire risk**: Wood is combustible, which increases the risk of fire and may require additional fireproofing measures.
4. **Shrinkage and warping**: Wood can expand, shrink, and warp over time, potentially leading to structural issues or cosmetic problems.
5. **Limited load-bearing capacity**: Timber has lower load-bearing capacity compared to steel, restricting design options for larger or more complex structures.

### Steel Framing

#### Advantages of Steel Framing

1. **Strength and durability**: Steel framing offers superior strength, stability, and resistance to weather, pests, and rot.
2. **Design flexibility**: Steel allows for longer spans and greater design freedom, making it suitable for modern architectural styles and large open spaces.
3. **Fire resistance**: Steel is non-combustible and offers better fire resistance, providing added safety and potentially lowering insurance costs.
4. **Minimal maintenance**: Steel frames are not susceptible to pests, rot, or warping, resulting in lower maintenance requirements.
5. **Sustainability (recyclability)**: Steel is highly recyclable and can be reused, reducing environmental impact and waste.

#### Disadvantages of Steel Framing

1. **Higher cost**: Steel framing is generally more expensive than timber framing, particularly for smaller residential projects or projects with more non-standard dimensions.
2. **Conductivity**: Steel is a conductor of heat and electricity, which can affect energy efficiency and require additional insulation measures.
3. **Aesthetics**: Steel frames may lack the warmth and natural appearance of timber, which may not appeal to some homeowners.
4. **Sound transmission**: Steel can transmit sound more effectively than wood, potentially requiring additional soundproofing measures.
5. **Weight and handling**: Steel frames are heavier and require specialized equipment for assembly and transport.

From an environment perspective, steel framing is preferred in certain environments due to its inherent properties and advantages. These include:
- Seismic Zones: Steel framing has excellent ductility and resilience, making it ideal for areas prone to earthquakes. It can absorb and dissipate seismic forces, reducing the risk of structural damage.
- Extreme Weather Conditions: Steel framing is resistant to high winds, hurricanes, and other severe weather conditions. It offers enhanced durability and stability in regions with harsh climates.
- Industrial and Commercial Structures: Steel framing is widely used in industrial and commercial construction due to its versatility, ability to span long distances without intermediate supports, and suitability for large open spaces.

Timber framing, on the other hand, is preferred in different environments due to its unique characteristics and benefits. These include:
- Residential Construction: Timber framing is commonly used in residential buildings, particularly single-family homes and low-rise structures. It provides a warm and natural aesthetic appeal to these spaces.
- Environmental Considerations: Timber framing is a renewable and sustainable building material. It has a lower carbon footprint compared to steel, as trees absorb carbon dioxide during their growth. Timber is preferable in jurisdictions that have carbon taxes or financial incentives for using renewable materials.
- Rural and Remote Areas: Timber framing is often preferred in rural and remote locations due to its availability and ease of transportation. It can be sourced locally, reducing logistical challenges and costs.

## Key Considerations for Structural Engineers

Structural stability and load-bearing capabilities of cold-formed steel are critical factors to consider. 

Cold-formed steel framing products have undergone extensive testing to determine their structural properties and performance. Structural engineers should consult manufacturer specifications and relevant design standards to ensure proper design and selection of cold-formed steel components.

The typical failure modes for cold formed steel framing include:
- **Buckling**: Cold-formed steel members are slender and susceptible to buckling under compressive loads. Engineers need to carefully analyze and design the framing system to prevent buckling failures, especially in columns and walls subjected to axial compression.
- **Lateral-Torsional Buckling**: Cold-formed steel beams and joists can experience lateral-torsional buckling, which occurs when the member twists and deflects laterally under combined bending and torsion. Engineers must evaluate the member's resistance to lateral-torsional buckling and employ appropriate bracing or design provisions to prevent failure.
- **Connection Failure**: Adequate connection design is crucial for the structural performance of cold-formed steel framing. Insufficiently designed or poorly executed connections can lead to local failures, compromising the overall stability and load transfer within the framing system.
- **Shear and Web Crippling**: Cold-formed steel members, such as studs and joists, can fail in shear or experience web crippling. Shear failures occur when the applied load exceeds the shear capacity of the member. Web crippling occurs when the flanges of a member buckle or deform due to concentrated loads from bearing elements or fasteners.
- **Material Yielding and Plastic Deformation**: Cold-formed steel can undergo yielding and plastic deformation under high loads. Engineers must carefully analyze and design members to ensure they remain within acceptable stress limits to avoid excessive deformation or failure.
- **Corrosion**: While cold-formed steel is more resistant to corrosion compared to hot-rolled steel, it is still susceptible to corrosion when exposed to moisture or corrosive environments. Corrosion can weaken the steel members and compromise their structural integrity.
- **Construction Tolerances**: Cold-formed steel framing requires precise fabrication and installation to maintain the intended design and structural performance. Deviations from design tolerances during manufacturing or construction can affect the overall stability and strength of the framing system.

The use of appropriate design software is crucial for the accurate analysis and design of cold-formed steel members. Specialized software packages, such as [ClearCalcs Calculations](https://clearcalcs.com/calculations), are compliant with the AISI (American Iron and Steel Institute) or AS/NZS (Australian and New Zealand Standards) design codes, and provide efficient tools for engineers to optimize their designs.

Before using design software, it is essential to familiarize oneself with the relevant building codes and regulations in the United States and Australia. 

Cold-formed steel design standards, such as AISI S100 in the United States and AS/NZS 4600 in Australia, provide guidelines for the safe and efficient use of cold-formed steel in construction. 

ClearCalcs has these standards built into the cold formed steel design software and can design a range of cold-formed steel structural components, including:
- [Cold-Formed Steel Beam (AS 4600:2018) - Joists, Rafters, Bearers, etc. to Australian Standards](https://clearcalcs.com/calculations/cfsSteelBeamAS4600-2018)
- [Cold-Formed Steel Column (AS 4600:2018) - Studs or Isolated Compression Members to Australian Standards](https://clearcalcs.com/calculations/cfsSteelColumnAU)
- [Cold-Formed Steel Design-Only Member (AS 4600:2018) - Design Using External FEA Results to Australian Standards](https://clearcalcs.com/calculations/cfsSteelMemberAS4600-2018)
- [Cold-Formed Steel Beam (AISI S100-16) - Joists, Rafters, Girders, etc to US Standards](https://clearcalcs.com/calculations/cfsSteelBeamAISI)
- [Cold-Formed Steel Column (AISI S100-16) - Studs or Isolated Compression Members to US Standards](https://clearcalcs.com/calculations/cfsSteelColumnAISI)

## Cold-Formed Steel Manufacturers

For structural engineers considering the use of cold-formed steel, it is essential to work with reputable manufacturers who produce high-quality products. 

In the United States, some well-known cold-formed steel manufacturers include BlueScope, Simpson Strong-Tie, and Clark Dietrich. These manufacturers adhere to stringent quality control measures and often have certifications, such as ISO 9001, which ensure their commitment to delivering reliable and consistent products. 

The below section summarises the main cold-formed steel manufacturers in Australia & the US.

### [BlueScope Steel](http://www.bluescopesteel.com.au/)
**Location:** US & Australia

**Certifications:** BlueScope Steel holds certifications such as ISO 9001 for quality management systems, ISO 14001 for environmental management systems, and AS/NZS 4801 for occupational health and safety management systems.

**Quality Control Measures:** BlueScope Steel maintains strict quality control measures throughout their manufacturing process, including material testing, adherence to Australian standards, and regular inspections to ensure high product quality and performance.

### [Lysaght](https://www.lysaght.com/)

Location: Australia

**Certifications:** Lysaght is certified with ISO 9001 for quality management systems and AS/NZS 4801 for occupational health and safety management systems.

**Quality Control Measures:** Lysaght upholds stringent quality control standards through comprehensive material testing, compliance with Australian standards, and continuous improvement initiatives. They also work with a network of authorized fabricators who undergo training and audits to ensure product quality.

### [ClarkDietrich Building Systems](https://www.clarkdietrich.com/)

**Location:** US

**Certifications:** ClarkDietrich holds certifications such as ISO 9001 for quality management systems, ISO 14001 for environmental management systems, and OSHA's SHARP (Safety and Health Achievement Recognition Program) certification.

_Quality Control Measures:_ ClarkDietrich implements comprehensive quality control measures, including rigorous material testing, in-process inspections, and compliance with industry standards like ASTM. They have a robust quality management system in place to monitor and maintain consistent product quality.

### [Simpson Strong-Tie](https://www.strongtie.com/)

**Location:** US

**Certifications:** Simpson Strong-Tie is certified with ISO 9001 for quality management systems and ISO 14001 for environmental management systems.

**Quality Control Measures:** Simpson Strong-Tie follows stringent quality control measures throughout their manufacturing process. This includes rigorous material testing, adherence to industry standards, and continuous product monitoring to ensure high-quality cold-formed steel components.

### [Steel Dynamics, Inc](https://stld.steeldynamics.com/)

**Location:** US

**Certifications:** Steel Dynamics, Inc. maintains certifications such as ISO 9001 for quality management systems and ISO 14001 for environmental management systems.

**Quality Control Measures:** Steel Dynamics implements rigorous quality control measures at every stage of their manufacturing process. This includes material testing, quality inspections, and compliance with relevant ASTM standards to guarantee product performance and reliability.

In Australia, although cold-formed steel is not standardized, structural engineers can refer to local manufacturers who specialize in cold-formed steel products. 

Collaborating with experienced manufacturers is vital to ensure access to reliable technical support, accurate product information, and compliance with local regulations. It's important to note that certifications and quality control measures may evolve over time, and it's advisable to visit the manufacturers' websites or contact them directly for the most up-to-date information regarding their certifications and quality control processes.

## Conclusion

Cold-formed steel is an increasingly popular choice for structural engineers in residential and light commercial projects. Its unique properties, including durability, strength, and resistance to fire and pests, make it an attractive alternative to traditional construction materials. Cold-formed steel framing offers advantages over wood framing, such as increased structural stability and design flexibility.

When using cold-formed steel, structural engineers must consider key factors such as design software, building codes, and manufacturer specifications. Utilizing specialized design software ensures accurate analysis and optimization of cold-formed steel members. Compliance with building codes, such as AISI S100 in the United States and AS/NZS 4600 in Australia, ensures the safety and quality of the project.

Choosing reputable cold-formed steel manufacturers is crucial for obtaining high-quality products. In the United States, manufacturers such as BlueScope, Simpson Strong-Tie, and Clark Dietrich are known for their commitment to quality and adherence to industry standards. In Australia, working with local manufacturers who specialize in cold-formed steel products ensures access to reliable technical support and compliance with local regulations.

In comparison to timber, cold-formed steel offers numerous benefits as a construction material. Its durability, strength, and resistance to fire and pests make it an ideal choice for residential and light commercial projects. By embracing this innovative material which can be easily designed for using ClearCalcs Calculations, engineers can achieve efficient and sustainable structures that meet the demands of the modern construction industry.

Structural engineers are encouraged to explore the possibilities of cold-formed steel for their next project. By embracing this innovative material, they can benefit from its superior properties, design flexibility, and sustainable attributes of CFS. As the construction industry continues to evolve, cold-formed steel offers a promising solution in the search for lightweight higher strength, corrosion & fire-resistant materials.



This article serves as a comprehensive guide for structural engineers who are interested in using cold-formed steel as a structural material in residential and light commercial projects. We will explore what cold-formed steel is, its benefits, its applications in building construction, and key considerations for engineers.

Cold-Formed Steel: A Guide for Residential and Light Commercial Projects

small_Home Roof Wood Beams.jpg

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Home Roof Wood Beams.jpg

## 1. What is Creep Deflection in Structural Wood?

Wood is a viscoelastic material, exhibiting both viscous and elastic characteristics when undergoing deformation. As a result, it suffers from creep behavior under long-term loading. Creep is the permanent sag caused by the stretching and adjusting of the wood fibers to the long-term loads on them, such as the weight of the member itself, the deck it supports, and other building components. It is a time-dependent deformation from constant stress that develops over years, and accelerates with frequent and drastic temperature and moisture content changes. Creep is an important factor to consider in the design and durability of timber structures. 

## 2. IBC 2018 Deflection Limits (1604.3)

Structural components must have enough stiffness to limit the deflections indicated in the IBC. For instance, members supporting brittle finishes (e.g. plaster walls) are limited to a lower allowable deflection, while members with flexible finishes are allowed a much higher allowable deflection limit. For D+L deflection, the incremental deflection is calculated and compared to the deflection limits. This includes the effects of creep but excludes instantaneous dead-load deflection, which takes place during construction and before deflection-sensitive elements are installed (e.g. glazing, masonry walls, marble flooring). For this reason, members subjected to D+L loads are allowed a larger deflection limit than those subjected to S,W,L, or Lr loads. 

## 3. Creep Deflection Calculation in IBC 2018 (1604.3)

The deflection limit for the D+(L+Lr) load combination only applies to the deflection due to the creep component of long-term dead load deflection plus the short-term live load deflection. For wood used under dry conditions, creep deflection is estimated as half of the immediate dead load deflection. When used at all other moisture conditions, it is estimated to be the same as the immediate dead load deflection. 

You can design wood beams and calculate deflection with [ClearCalcs Wood Beam Calculator here](https://clearcalcs.com/calculations/us/timberBeamASD).

## 4. Creep Deflection Calculation in NDS 2018 (3.5.2)

The total deflection of a member is calculated as the sum of the deflection due to short term load and the immediate deflection due to long-term load, where the latter is multiplied by a time dependent factor. As mentioned above, creep is a time-dependent deformation that accelerates with frequent and drastic temperature and moisture content changes. As such, the immediate deflection due to long-term load is increased by half for dry wood, and doubled for glue laminated timber and wet wood. Since deflection limits are typically set by the IBC, which considers only the creep component of deflection, the NDS formula results in the same deflection calculation as the IBC. 


Understand Creep Deflection Calculation in Structural Design | Learn about creep deflection and its impact on structural elements. Discover how to account for creep deflection in your design calculations to ensure long-term stability and performance.

Creep Deflection in Structural Wood Beam Design

Deform bar steel bars used in concrete footings 

small_Deform bar steel bars used in concrete footings

thumbnail_Deform bar steel bars used in concrete footings

Deform bar steel bars used in concrete footings

## What is Development Length?

Steel reinforcement (rebar) in concrete footings generally acts in tension to resist bending loads that arise as the footing spreads loads uniformly over the soil underneath. However, those tension loads have to be transmitted between the concrete (where the load is applied) and the rebar. For this to happen, there has to be enough "grip" between the concrete and the rebar - otherwise the rebar would just get ripped right out of the concrete! Because rebar breaking out of concrete is generally an undesirable scenario (think a sudden bang with no warning), engineers generally ensure that there's enough grip between concrete and rebar to ensure that the rebar reaches its full yield strength. That lets us use the full strength of the steel for greater efficiency, and is accompanied by large movements that'll give plenty of warning to occupants. 

The length of rebar required to achieve the necessary grip is what we call the development length. Since the rebar can be considered "ineffective" over its development length, it's desirable to minimize this length as much as possible. The most common way to reduce this length is to add ribs to the rebar, which grip the concrete around them. Another solution often employed is to "hook" bars by bending the ends 90 degrees, which significantly reduces the required development length at the expense of having to bend rebar and fitting the "hooks". Note that the bigger the bar, the longer the development length required, as they can take more force!

## Code Requirements for Development Length

As previously described, it's generally very desirable to "fully develop" bars, which means providing enough development length that the rebar can reach its full yield strength before ripping out the concrete. This is also reflected in building codes, which will almost always require that rebar be fully developed. For instance, ACI 318-19, the concrete design standard principally used in the USA, provides equations for development length that directly depend on the yield strength of the rebar. The equation below is taken directly from ACI 318-19, as implemented in ClearCalcs.

![ACI 318-19 Development Length Equation](https://clearcalcs-prod2-cms.s3.amazonaws.com/ACI_318_19_Development_Length_Equation_42ad0645fa.png)

Providing this development length is an  essential part of reinforced concrete design. Formulas and methods used to analyze the strength of concrete members are practically all dependent on the assumption that the rebar can reach its full yield strength. Thus, not providing enough development length can very much lead to premature failures.

However, to account for the fact that it may be impractical to reach full development lengths in some situations (the largest bars can require over 10 feet of development length!), the code also allows reducing the development length, in some cases, as a proportion of the required steel vs what is provided. So if far more steel is provided than is required, the development length may be reduced - but only down to a hard limit of 12 inches, and it can't apply to reinforcement provided for things like increased ductility or when resisting seismic loads.

## Development Length in Footings

When calculating the rebar required in footings, we look at a critical section for bending moment, generated by the action of load being spread uniformly from the column to the entire area of the footing. As you can see on the image below, the available length for development of the rebar is the distance between the column face and the footing edge, less the concrete cover.

![Development Length in Footings](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Development_Length_in_Footings_58821df030.png)

In larger footings such as used in commercial buildings, it's generally never an issue to achieve development of the rebar. However, in smaller footings such as in residential construction, this can be a problem. Even when using small bar sizes and applying all the reductions allowed by the ACI 318-19 code, we're still left with the 12" hard limit on development length, which, if combined with 3" cover and assuming a 6"x6" post, means we need a footing at least 3 feet wide. This may often be larger than typical construction practices, which have been proven time and time again to be sufficient. So how do we accommodate this? Let's look at one solution...

## Plain Concrete - No Development Required!

If we don't want to deal with rebar development length, there's one simple solution: skip the rebar! Indeed, the ACI code specifically allows concrete footings to be designed without any rebar, using the small tensile capacity of concrete to resist the bending loads we discussed previously. In reality, this winds up being more of an "arch" action, where load gets spread in compression diagonally into the soil below. When using these provisions, there's nothing saying we can't actually still include rebar in there - just that we can't consider it to strengthen the footing.

Specifically with small residential footings where loads are small and the footings relatively "stubby", it's almost always the case that footings will be adequate when considering only the plain concrete. So if you've had the same typical detail for small footings calling out a small grid of #5 rebars for the last two decades and were surprised to find that it wasn't passing due to development length, fear not! The best way to handle this in ClearCalcs is to design as Plain Concrete, and simply to specify your desired rebar pattern in your drawings afterwards. 

Try [ClearCalcs Spread Footing (ACI 318-14) Calculator](https://clearcalcs.com/calculations/us/foundationsSpreadFootingUSA) now!

![Plain Concrete selection in ClearCalcs Concrete Footing Calculator](https://clearcalcs-prod2-cms.s3.ap-southeast-2.amazonaws.com/Plain_Concrete_selection_in_Clear_Calcs_Concrete_Footing_Calculator_9b788ef148.png)

Development Length in Footings Explained | Learn about the importance of development length in reinforced concrete footings. Understand the code requirements, factors affecting development length, and solutions to accommodate it in your footing design for safe and efficient construction.

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